DEV-1761: New rules API (#118)

* DEV-1761: Clean up Ruleset interface (#115)

* remove legacy ruleset types and simplify ruleset interface

* remove unnecessary settings argument from Ruleset interface

* decouple rules.Settings from client API and store settings as strings

* DEV 1761: Add new BoardState and Point fields (#117)

* add Point.TTL, Point.Value, GameState and PointState to BoardState

* allow maps to access BoardState.GameState,PointState

* add PreUpdateBoard and refactor snail_mode with it

* fix bug where an extra turn was printed to the console

* fix formatting

* fix lint errors

Co-authored-by: JonathanArns <jonathan.arns@googlemail.com>

board.go

@@ -2,6 +2,9 @@ package rules
 
 import "fmt"
 
+// BoardState represents the internal state of a game board.
+// NOTE: use NewBoardState to construct these to ensure fields are initialized
+// correctly and that tests are resilient to changes to this type.
 type BoardState struct {
 	Turn    int
 	Height  int
@@ -9,15 +12,26 @@ type BoardState struct {
 	Food    []Point
 	Snakes  []Snake
 	Hazards []Point
+
+	// Generic game-level state for maps and rules stages to persist data between turns.
+	GameState map[string]string
+
+	// Numeric state keyed to specific points, also persisted between turns.
+	PointState map[Point]int
 }
 
 type Point struct {
-	X int
+	X     int `json:"X"`
-	Y int
+	Y     int `json:"Y"`
+	TTL   int `json:"TTL,omitempty"`
+	Value int `json:"Value,omitempty"`
 }
 
 // Makes it easier to copy sample points out of Go logs and test failures.
 func (p Point) GoString() string {
+	if p.TTL != 0 || p.Value != 0 {
+		return fmt.Sprintf("{X:%d, Y:%d, TTL:%d, Value:%d}", p.X, p.Y, p.TTL, p.Value)
+	}
 	return fmt.Sprintf("{X:%d, Y:%d}", p.X, p.Y)
 }
 
@@ -39,6 +53,8 @@ func NewBoardState(width, height int) *BoardState {
 		Food:       []Point{},
 		Snakes:     []Snake{},
 		Hazards:    []Point{},
+		GameState:  map[string]string{},
+		PointState: map[Point]int{},
 	}
 }
 
@@ -51,6 +67,14 @@ func (prevState *BoardState) Clone() *BoardState {
 		Food:       append([]Point{}, prevState.Food...),
 		Snakes:     make([]Snake, len(prevState.Snakes)),
 		Hazards:    append([]Point{}, prevState.Hazards...),
+		GameState:  make(map[string]string, len(prevState.GameState)),
+		PointState: make(map[Point]int, len(prevState.PointState)),
+	}
+	for key, value := range prevState.GameState {
+		nextState.GameState[key] = value
+	}
+	for key, value := range prevState.PointState {
+		nextState.PointState[key] = value
 	}
 	for i := 0; i < len(prevState.Snakes); i++ {
 		nextState.Snakes[i].ID = prevState.Snakes[i].ID
@@ -63,6 +87,42 @@ func (prevState *BoardState) Clone() *BoardState {
 	return nextState
 }
 
+// Builder method to set Turn and return the modified BoardState.
+func (state *BoardState) WithTurn(turn int) *BoardState {
+	state.Turn = turn
+	return state
+}
+
+// Builder method to set Food and return the modified BoardState.
+func (state *BoardState) WithFood(food []Point) *BoardState {
+	state.Food = food
+	return state
+}
+
+// Builder method to set Hazards and return the modified BoardState.
+func (state *BoardState) WithHazards(hazards []Point) *BoardState {
+	state.Hazards = hazards
+	return state
+}
+
+// Builder method to set Snakes and return the modified BoardState.
+func (state *BoardState) WithSnakes(snakes []Snake) *BoardState {
+	state.Snakes = snakes
+	return state
+}
+
+// Builder method to set State and return the modified BoardState.
+func (state *BoardState) WithGameState(gameState map[string]string) *BoardState {
+	state.GameState = gameState
+	return state
+}
+
+// Builder method to set PointState and return the modified BoardState.
+func (state *BoardState) WithPointState(pointState map[Point]int) *BoardState {
+	state.PointState = pointState
+	return state
+}
+
 // CreateDefaultBoardState is a convenience function for fully initializing a
 // "default" board state with snakes and food.
 // In a real game, the engine may generate the board without calling this
@@ -120,16 +180,16 @@ func PlaceSnakesFixed(rand Rand, b *BoardState, snakeIDs []string) error {
 	// Create start 8 points
 	mn, md, mx := 1, (b.Width-1)/2, b.Width-2
 	cornerPoints := []Point{
-		{mn, mn},
+		{X: mn, Y: mn},
-		{mn, mx},
+		{X: mn, Y: mx},
-		{mx, mn},
+		{X: mx, Y: mn},
-		{mx, mx},
+		{X: mx, Y: mx},
 	}
 	cardinalPoints := []Point{
-		{mn, md},
+		{X: mn, Y: md},
-		{md, mn},
+		{X: md, Y: mn},
-		{md, mx},
+		{X: md, Y: mx},
-		{mx, md},
+		{X: mx, Y: md},
 	}
 
 	// Sanity check
@@ -325,7 +385,7 @@ func PlaceFoodAutomatically(rand Rand, b *BoardState) error {
 
 // Deprecated: will be replaced by maps.PlaceFoodFixed
 func PlaceFoodFixed(rand Rand, b *BoardState) error {
-	centerCoord := Point{(b.Width - 1) / 2, (b.Height - 1) / 2}
+	centerCoord := Point{X: (b.Width - 1) / 2, Y: (b.Height - 1) / 2}
 
 	isSmallBoard := b.Width*b.Height < BoardSizeMedium*BoardSizeMedium
 	// Up to 4 snakes can be placed such that food is nearby on small boards.
@@ -335,10 +395,10 @@ func PlaceFoodFixed(rand Rand, b *BoardState) error {
 		for i := 0; i < len(b.Snakes); i++ {
 			snakeHead := b.Snakes[i].Body[0]
 			possibleFoodLocations := []Point{
-				{snakeHead.X - 1, snakeHead.Y - 1},
+				{X: snakeHead.X - 1, Y: snakeHead.Y - 1},
-				{snakeHead.X - 1, snakeHead.Y + 1},
+				{X: snakeHead.X - 1, Y: snakeHead.Y + 1},
-				{snakeHead.X + 1, snakeHead.Y - 1},
+				{X: snakeHead.X + 1, Y: snakeHead.Y - 1},
-				{snakeHead.X + 1, snakeHead.Y + 1},
+				{X: snakeHead.X + 1, Y: snakeHead.Y + 1},
 			}
 
 			// Remove any invalid/unwanted positions
@@ -448,7 +508,7 @@ func GetEvenUnoccupiedPoints(b *BoardState) []Point {
 
 // removeCenterCoord filters out the board's center point from a list of points.
 func removeCenterCoord(b *BoardState, points []Point) []Point {
-	centerCoord := Point{(b.Width - 1) / 2, (b.Height - 1) / 2}
+	centerCoord := Point{X: (b.Width - 1) / 2, Y: (b.Height - 1) / 2}
 	var noCenterPoints []Point
 	for _, p := range points {
 		if p != centerCoord {

board_test.go

@@ -8,6 +8,30 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestBoardStateClone(t *testing.T) {
+	empty := &BoardState{}
+	require.Equal(t, NewBoardState(0, 0), empty.Clone())
+
+	full := NewBoardState(11, 11).
+		WithTurn(99).
+		WithFood([]Point{{X: 1, Y: 2, TTL: 10, Value: 100}}).
+		WithHazards([]Point{{X: 3, Y: 4, TTL: 5, Value: 50}}).
+		WithSnakes([]Snake{
+			{
+				ID:               "1",
+				Body:             []Point{{X: 1, Y: 2}},
+				Health:           99,
+				EliminatedCause:  EliminatedByCollision,
+				EliminatedOnTurn: 45,
+				EliminatedBy:     "2",
+			},
+		}).
+		WithGameState(map[string]string{"example": "game data"}).
+		WithPointState(map[Point]int{{X: 1, Y: 1}: 42})
+
+	require.Equal(t, full, full.Clone())
+}
+
 func TestDev1235(t *testing.T) {
 	// Small boards should no longer error and only get 1 food when num snakes > 4
 	state, err := CreateDefaultBoardState(MaxRand, BoardSizeSmall, BoardSizeSmall, []string{
@@ -346,23 +370,23 @@ func TestPlaceSnake(t *testing.T) {
 	boardState := NewBoardState(BoardSizeSmall, BoardSizeSmall)
 	require.Empty(t, boardState.Snakes)
 
-	_ = PlaceSnake(boardState, "a", []Point{{0, 0}, {1, 0}, {1, 1}})
+	_ = PlaceSnake(boardState, "a", []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}})
 
 	require.Len(t, boardState.Snakes, 1)
 	require.Equal(t, Snake{
 		ID:              "a",
-		Body:            []Point{{0, 0}, {1, 0}, {1, 1}},
+		Body:            []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}},
 		Health:          SnakeMaxHealth,
 		EliminatedCause: NotEliminated,
 		EliminatedBy:    "",
 	}, boardState.Snakes[0])
 
-	_ = PlaceSnake(boardState, "b", []Point{{0, 2}, {1, 2}, {3, 2}})
+	_ = PlaceSnake(boardState, "b", []Point{{X: 0, Y: 2}, {X: 1, Y: 2}, {X: 3, Y: 2}})
 
 	require.Len(t, boardState.Snakes, 2)
 	require.Equal(t, Snake{
 		ID:              "b",
-		Body:            []Point{{0, 2}, {1, 2}, {3, 2}},
+		Body:            []Point{{X: 0, Y: 2}, {X: 1, Y: 2}, {X: 3, Y: 2}},
 		Health:          SnakeMaxHealth,
 		EliminatedCause: NotEliminated,
 		EliminatedBy:    "",
@@ -411,9 +435,9 @@ func TestPlaceFood(t *testing.T) {
 				Width:  BoardSizeSmall,
 				Height: BoardSizeSmall,
 				Snakes: []Snake{
-					{Body: []Point{{5, 1}}},
+					{Body: []Point{{X: 5, Y: 1}}},
-					{Body: []Point{{5, 3}}},
+					{Body: []Point{{X: 5, Y: 3}}},
-					{Body: []Point{{5, 5}}},
+					{Body: []Point{{X: 5, Y: 5}}},
 				},
 			},
 			4, // +1 because of fixed spawn locations
@@ -423,14 +447,14 @@ func TestPlaceFood(t *testing.T) {
 				Width:  BoardSizeMedium,
 				Height: BoardSizeMedium,
 				Snakes: []Snake{
-					{Body: []Point{{1, 1}}},
+					{Body: []Point{{X: 1, Y: 1}}},
-					{Body: []Point{{1, 5}}},
+					{Body: []Point{{X: 1, Y: 5}}},
-					{Body: []Point{{1, 9}}},
+					{Body: []Point{{X: 1, Y: 9}}},
-					{Body: []Point{{5, 1}}},
+					{Body: []Point{{X: 5, Y: 1}}},
-					{Body: []Point{{5, 9}}},
+					{Body: []Point{{X: 5, Y: 9}}},
-					{Body: []Point{{9, 1}}},
+					{Body: []Point{{X: 9, Y: 1}}},
-					{Body: []Point{{9, 5}}},
+					{Body: []Point{{X: 9, Y: 5}}},
-					{Body: []Point{{9, 9}}},
+					{Body: []Point{{X: 9, Y: 9}}},
 				},
 			},
 			9, // +1 because of fixed spawn locations
@@ -440,12 +464,12 @@ func TestPlaceFood(t *testing.T) {
 				Width:  BoardSizeLarge,
 				Height: BoardSizeLarge,
 				Snakes: []Snake{
-					{Body: []Point{{1, 1}}},
+					{Body: []Point{{X: 1, Y: 1}}},
-					{Body: []Point{{1, 9}}},
+					{Body: []Point{{X: 1, Y: 9}}},
-					{Body: []Point{{1, 17}}},
+					{Body: []Point{{X: 1, Y: 17}}},
-					{Body: []Point{{17, 1}}},
+					{Body: []Point{{X: 17, Y: 1}}},
-					{Body: []Point{{17, 9}}},
+					{Body: []Point{{X: 17, Y: 9}}},
-					{Body: []Point{{17, 17}}},
+					{Body: []Point{{X: 17, Y: 17}}},
 				},
 			},
 			7, // +1 because of fixed spawn locations
@@ -478,7 +502,7 @@ func TestPlaceFoodFixed(t *testing.T) {
 				Width:  BoardSizeSmall,
 				Height: BoardSizeSmall,
 				Snakes: []Snake{
-					{Body: []Point{{1, 3}}},
+					{Body: []Point{{X: 1, Y: 3}}},
 				},
 			},
 		},
@@ -487,10 +511,10 @@ func TestPlaceFoodFixed(t *testing.T) {
 				Width:  BoardSizeMedium,
 				Height: BoardSizeMedium,
 				Snakes: []Snake{
-					{Body: []Point{{1, 1}}},
+					{Body: []Point{{X: 1, Y: 1}}},
-					{Body: []Point{{1, 5}}},
+					{Body: []Point{{X: 1, Y: 5}}},
-					{Body: []Point{{9, 5}}},
+					{Body: []Point{{X: 9, Y: 5}}},
-					{Body: []Point{{9, 9}}},
+					{Body: []Point{{X: 9, Y: 9}}},
 				},
 			},
 		},
@@ -499,14 +523,14 @@ func TestPlaceFoodFixed(t *testing.T) {
 				Width:  BoardSizeLarge,
 				Height: BoardSizeLarge,
 				Snakes: []Snake{
-					{Body: []Point{{1, 1}}},
+					{Body: []Point{{X: 1, Y: 1}}},
-					{Body: []Point{{1, 9}}},
+					{Body: []Point{{X: 1, Y: 9}}},
-					{Body: []Point{{1, 17}}},
+					{Body: []Point{{X: 1, Y: 17}}},
-					{Body: []Point{{9, 1}}},
+					{Body: []Point{{X: 9, Y: 1}}},
-					{Body: []Point{{9, 17}}},
+					{Body: []Point{{X: 9, Y: 17}}},
-					{Body: []Point{{17, 1}}},
+					{Body: []Point{{X: 17, Y: 1}}},
-					{Body: []Point{{17, 9}}},
+					{Body: []Point{{X: 17, Y: 9}}},
-					{Body: []Point{{17, 17}}},
+					{Body: []Point{{X: 17, Y: 17}}},
 				},
 			},
 		},
@@ -519,16 +543,16 @@ func TestPlaceFoodFixed(t *testing.T) {
 		require.NoError(t, err)
 		require.Equal(t, len(test.BoardState.Snakes)+1, len(test.BoardState.Food))
 
-		midPoint := Point{(test.BoardState.Width - 1) / 2, (test.BoardState.Height - 1) / 2}
+		midPoint := Point{X: (test.BoardState.Width - 1) / 2, Y: (test.BoardState.Height - 1) / 2}
 
 		// Make sure every snake has food within 2 moves of it
 		for _, snake := range test.BoardState.Snakes {
 			head := snake.Body[0]
 
-			bottomLeft := Point{head.X - 1, head.Y - 1}
+			bottomLeft := Point{X: head.X - 1, Y: head.Y - 1}
-			topLeft := Point{head.X - 1, head.Y + 1}
+			topLeft := Point{X: head.X - 1, Y: head.Y + 1}
-			bottomRight := Point{head.X + 1, head.Y - 1}
+			bottomRight := Point{X: head.X + 1, Y: head.Y - 1}
-			topRight := Point{head.X + 1, head.Y + 1}
+			topRight := Point{X: head.X + 1, Y: head.Y + 1}
 
 			foundFoodInTwoMoves := false
 			for _, food := range test.BoardState.Food {
@@ -559,7 +583,7 @@ func TestPlaceFoodFixedNoRoom(t *testing.T) {
 		Width:  3,
 		Height: 3,
 		Snakes: []Snake{
-			{Body: []Point{{1, 1}}},
+			{Body: []Point{{X: 1, Y: 1}}},
 		},
 		Food: []Point{},
 	}
@@ -572,10 +596,10 @@ func TestPlaceFoodFixedNoRoom_Corners(t *testing.T) {
 		Width:  7,
 		Height: 7,
 		Snakes: []Snake{
-			{Body: []Point{{1, 1}}},
+			{Body: []Point{{X: 1, Y: 1}}},
-			{Body: []Point{{1, 5}}},
+			{Body: []Point{{X: 1, Y: 5}}},
-			{Body: []Point{{5, 1}}},
+			{Body: []Point{{X: 5, Y: 1}}},
-			{Body: []Point{{5, 5}}},
+			{Body: []Point{{X: 5, Y: 5}}},
 		},
 		Food: []Point{},
 	}
@@ -597,10 +621,10 @@ func TestPlaceFoodFixedNoRoom_Corners(t *testing.T) {
 	require.Error(t, err)
 
 	expectedFood := []Point{
-		{0, 2}, {2, 0}, // Snake @ {1, 1}
+		{X: 0, Y: 2}, {X: 2, Y: 0}, // Snake @ {X: 1, Y: 1}
-		{0, 4}, {2, 6}, // Snake @ {1, 5}
+		{X: 0, Y: 4}, {X: 2, Y: 6}, // Snake @ {X: 1, Y: 5}
-		{4, 0}, {6, 2}, // Snake @ {5, 1}
+		{X: 4, Y: 0}, {X: 6, Y: 2}, // Snake @ {X: 5, Y: 1}
-		{4, 6}, {6, 4}, // Snake @ {5, 5}
+		{X: 4, Y: 6}, {X: 6, Y: 4}, // Snake @ {X: 5, Y: 5}
 	}
 	sortPoints(expectedFood)
 	sortPoints(boardState.Food)
@@ -612,10 +636,10 @@ func TestPlaceFoodFixedNoRoom_Cardinal(t *testing.T) {
 		Width:  11,
 		Height: 11,
 		Snakes: []Snake{
-			{Body: []Point{{1, 5}}},
+			{Body: []Point{{X: 1, Y: 5}}},
-			{Body: []Point{{5, 1}}},
+			{Body: []Point{{X: 5, Y: 1}}},
-			{Body: []Point{{5, 9}}},
+			{Body: []Point{{X: 5, Y: 9}}},
-			{Body: []Point{{9, 5}}},
+			{Body: []Point{{X: 9, Y: 5}}},
 		},
 		Food: []Point{},
 	}
@@ -637,10 +661,10 @@ func TestPlaceFoodFixedNoRoom_Cardinal(t *testing.T) {
 	require.Error(t, err)
 
 	expectedFood := []Point{
-		{0, 4}, {0, 6}, // Snake @ {1, 5}
+		{X: 0, Y: 4}, {X: 0, Y: 6}, // Snake @ {X: 1, Y: 5}
-		{4, 0}, {6, 0}, // Snake @ {5, 1}
+		{X: 4, Y: 0}, {X: 6, Y: 0}, // Snake @ {X: 5, Y: 1}
-		{4, 10}, {6, 10}, // Snake @ {5, 9}
+		{X: 4, Y: 10}, {X: 6, Y: 10}, // Snake @ {X: 5, Y: 9}
-		{10, 4}, {10, 6}, // Snake @ {9, 5}
+		{X: 10, Y: 4}, {X: 10, Y: 6}, // Snake @ {X: 9, Y: 5}
 	}
 	sortPoints(expectedFood)
 	sortPoints(boardState.Food)
@@ -653,15 +677,15 @@ func TestGetDistanceBetweenPoints(t *testing.T) {
 		B        Point
 		Expected int
 	}{
-		{Point{0, 0}, Point{0, 0}, 0},
+		{Point{X: 0, Y: 0}, Point{X: 0, Y: 0}, 0},
-		{Point{0, 0}, Point{1, 0}, 1},
+		{Point{X: 0, Y: 0}, Point{X: 1, Y: 0}, 1},
-		{Point{0, 0}, Point{0, 1}, 1},
+		{Point{X: 0, Y: 0}, Point{X: 0, Y: 1}, 1},
-		{Point{0, 0}, Point{1, 1}, 2},
+		{Point{X: 0, Y: 0}, Point{X: 1, Y: 1}, 2},
-		{Point{0, 0}, Point{4, 4}, 8},
+		{Point{X: 0, Y: 0}, Point{X: 4, Y: 4}, 8},
-		{Point{0, 0}, Point{4, 6}, 10},
+		{Point{X: 0, Y: 0}, Point{X: 4, Y: 6}, 10},
-		{Point{8, 0}, Point{8, 0}, 0},
+		{Point{X: 8, Y: 0}, Point{X: 8, Y: 0}, 0},
-		{Point{8, 0}, Point{8, 8}, 8},
+		{Point{X: 8, Y: 0}, Point{X: 8, Y: 8}, 8},
-		{Point{8, 0}, Point{0, 8}, 16},
+		{Point{X: 8, Y: 0}, Point{X: 0, Y: 8}, 16},
 	}
 
 	for _, test := range tests {
@@ -704,20 +728,20 @@ func TestGetUnoccupiedPoints(t *testing.T) {
 				Height: 1,
 				Width:  1,
 			},
-			[]Point{{0, 0}},
+			[]Point{{X: 0, Y: 0}},
 		},
 		{
 			&BoardState{
 				Height: 1,
 				Width:  2,
 			},
-			[]Point{{0, 0}, {1, 0}},
+			[]Point{{X: 0, Y: 0}, {X: 1, Y: 0}},
 		},
 		{
 			&BoardState{
 				Height: 1,
 				Width:  1,
-				Food:   []Point{{0, 0}, {101, 202}, {-4, -5}},
+				Food:   []Point{{X: 0, Y: 0}, {X: 101, Y: 202}, {X: -4, Y: -5}},
 			},
 			[]Point{},
 		},
@@ -725,15 +749,15 @@ func TestGetUnoccupiedPoints(t *testing.T) {
 			&BoardState{
 				Height: 2,
 				Width:  2,
-				Food:   []Point{{0, 0}, {1, 0}},
+				Food:   []Point{{X: 0, Y: 0}, {X: 1, Y: 0}},
 			},
-			[]Point{{0, 1}, {1, 1}},
+			[]Point{{X: 0, Y: 1}, {X: 1, Y: 1}},
 		},
 		{
 			&BoardState{
 				Height: 2,
 				Width:  2,
-				Food:   []Point{{0, 0}, {0, 1}, {1, 0}, {1, 1}},
+				Food:   []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 1, Y: 0}, {X: 1, Y: 1}},
 			},
 			[]Point{},
 		},
@@ -742,38 +766,38 @@ func TestGetUnoccupiedPoints(t *testing.T) {
 				Height: 4,
 				Width:  1,
 				Snakes: []Snake{
-					{Body: []Point{{0, 0}}},
+					{Body: []Point{{X: 0, Y: 0}}},
 				},
 			},
-			[]Point{{0, 1}, {0, 2}, {0, 3}},
+			[]Point{{X: 0, Y: 1}, {X: 0, Y: 2}, {X: 0, Y: 3}},
 		},
 		{
 			&BoardState{
 				Height: 2,
 				Width:  3,
 				Snakes: []Snake{
-					{Body: []Point{{0, 0}, {1, 0}, {1, 1}}},
+					{Body: []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}}},
 				},
 			},
-			[]Point{{0, 1}, {2, 0}, {2, 1}},
+			[]Point{{X: 0, Y: 1}, {X: 2, Y: 0}, {X: 2, Y: 1}},
 		},
 		{
 			&BoardState{
 				Height: 2,
 				Width:  3,
-				Food:   []Point{{0, 0}, {1, 0}, {1, 1}, {2, 0}},
+				Food:   []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}, {X: 2, Y: 0}},
 				Snakes: []Snake{
-					{Body: []Point{{0, 0}, {1, 0}, {1, 1}}},
+					{Body: []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}}},
-					{Body: []Point{{0, 1}}},
+					{Body: []Point{{X: 0, Y: 1}}},
 				},
 			},
-			[]Point{{2, 1}},
+			[]Point{{X: 2, Y: 1}},
 		},
 		{
 			&BoardState{
 				Height:  1,
 				Width:   1,
-				Hazards: []Point{{0, 0}},
+				Hazards: []Point{{X: 0, Y: 0}},
 			},
 			[]Point{},
 		},
@@ -781,22 +805,22 @@ func TestGetUnoccupiedPoints(t *testing.T) {
 			&BoardState{
 				Height:  2,
 				Width:   2,
-				Hazards: []Point{{1, 1}},
+				Hazards: []Point{{X: 1, Y: 1}},
 			},
-			[]Point{{0, 0}, {0, 1}, {1, 0}},
+			[]Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 1, Y: 0}},
 		},
 		{
 			&BoardState{
 				Height: 2,
 				Width:  3,
-				Food:   []Point{{1, 1}, {2, 0}},
+				Food:   []Point{{X: 1, Y: 1}, {X: 2, Y: 0}},
 				Snakes: []Snake{
-					{Body: []Point{{0, 0}, {1, 0}, {1, 1}}},
+					{Body: []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}}},
-					{Body: []Point{{0, 1}}},
+					{Body: []Point{{X: 0, Y: 1}}},
 				},
-				Hazards: []Point{{0, 0}, {1, 0}},
+				Hazards: []Point{{X: 0, Y: 0}, {X: 1, Y: 0}},
 			},
-			[]Point{{2, 1}},
+			[]Point{{X: 2, Y: 1}},
 		},
 	}
 
@@ -819,20 +843,20 @@ func TestGetEvenUnoccupiedPoints(t *testing.T) {
 				Height: 1,
 				Width:  1,
 			},
-			[]Point{{0, 0}},
+			[]Point{{X: 0, Y: 0}},
 		},
 		{
 			&BoardState{
 				Height: 2,
 				Width:  2,
 			},
-			[]Point{{0, 0}, {1, 1}},
+			[]Point{{X: 0, Y: 0}, {X: 1, Y: 1}},
 		},
 		{
 			&BoardState{
 				Height: 1,
 				Width:  1,
-				Food:   []Point{{0, 0}, {101, 202}, {-4, -5}},
+				Food:   []Point{{X: 0, Y: 0}, {X: 101, Y: 202}, {X: -4, Y: -5}},
 			},
 			[]Point{},
 		},
@@ -840,15 +864,15 @@ func TestGetEvenUnoccupiedPoints(t *testing.T) {
 			&BoardState{
 				Height: 2,
 				Width:  2,
-				Food:   []Point{{0, 0}, {1, 0}},
+				Food:   []Point{{X: 0, Y: 0}, {X: 1, Y: 0}},
 			},
-			[]Point{{1, 1}},
+			[]Point{{X: 1, Y: 1}},
 		},
 		{
 			&BoardState{
 				Height: 4,
 				Width:  4,
-				Food:   []Point{{0, 0}, {0, 2}, {1, 1}, {1, 3}, {2, 0}, {2, 2}, {3, 1}, {3, 3}},
+				Food:   []Point{{X: 0, Y: 0}, {X: 0, Y: 2}, {X: 1, Y: 1}, {X: 1, Y: 3}, {X: 2, Y: 0}, {X: 2, Y: 2}, {X: 3, Y: 1}, {X: 3, Y: 3}},
 			},
 			[]Point{},
 		},
@@ -857,32 +881,32 @@ func TestGetEvenUnoccupiedPoints(t *testing.T) {
 				Height: 4,
 				Width:  1,
 				Snakes: []Snake{
-					{Body: []Point{{0, 0}}},
+					{Body: []Point{{X: 0, Y: 0}}},
 				},
 			},
-			[]Point{{0, 2}},
+			[]Point{{X: 0, Y: 2}},
 		},
 		{
 			&BoardState{
 				Height: 2,
 				Width:  3,
 				Snakes: []Snake{
-					{Body: []Point{{0, 0}, {1, 0}, {1, 1}}},
+					{Body: []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}}},
 				},
 			},
-			[]Point{{2, 0}},
+			[]Point{{X: 2, Y: 0}},
 		},
 		{
 			&BoardState{
 				Height: 2,
 				Width:  3,
-				Food:   []Point{{0, 0}, {1, 0}, {1, 1}, {2, 1}},
+				Food:   []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}, {X: 2, Y: 1}},
 				Snakes: []Snake{
-					{Body: []Point{{0, 0}, {1, 0}, {1, 1}}},
+					{Body: []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}}},
-					{Body: []Point{{0, 1}}},
+					{Body: []Point{{X: 0, Y: 1}}},
 				},
 			},
-			[]Point{{2, 0}},
+			[]Point{{X: 2, Y: 0}},
 		},
 	}
 
@@ -902,7 +926,7 @@ func TestPlaceFoodRandomly(t *testing.T) {
 		Height: 1,
 		Width:  3,
 		Snakes: []Snake{
-			{Body: []Point{{1, 0}}},
+			{Body: []Point{{X: 1, Y: 0}}},
 		},
 	}
 	// Food should never spawn, no room

cases_test.go

@@ -29,8 +29,8 @@ func (gc *gameTestCase) requireValidNextState(t *testing.T, r Ruleset) {
 	t.Helper()
 	t.Run(gc.name, func(t *testing.T) {
 		t.Helper()
-		prev := gc.prevState.Clone() // clone to protect against mutation (so we can ru-use test cases)
+		prev := gc.prevState.Clone() // clone to protect against mutation (so we can re-use test cases)
-		nextState, err := r.CreateNextBoardState(prev, gc.moves)
+		_, nextState, err := r.Execute(prev, gc.moves)
 		require.Equal(t, gc.expectedError, err)
 		if gc.expectedState != nil {
 			require.Equal(t, gc.expectedState.Width, nextState.Width)

cli/commands/play.go

@@ -88,7 +88,9 @@ func NewPlayCommand() *cobra.Command {
 			if err := gameState.Initialize(); err != nil {
 				log.ERROR.Fatalf("Error initializing game: %v", err)
 			}
-			gameState.Run()
+			if err := gameState.Run(); err != nil {
+				log.ERROR.Fatalf("Error running game: %v", err)
+			}
 		},
 	}
 
@@ -143,7 +145,6 @@ func (gameState *GameState) Initialize() error {
 
 	// Create settings object
 	gameState.settings = map[string]string{
-		rules.ParamGameType:            gameState.GameType,
 		rules.ParamFoodSpawnChance:     fmt.Sprint(gameState.FoodSpawnChance),
 		rules.ParamMinimumFood:         fmt.Sprint(gameState.MinimumFood),
 		rules.ParamHazardDamagePerTurn: fmt.Sprint(gameState.HazardDamagePerTurn),
@@ -155,7 +156,7 @@ func (gameState *GameState) Initialize() error {
 		WithSeed(gameState.Seed).
 		WithParams(gameState.settings).
 		WithSolo(len(gameState.URLs) < 2).
-		Ruleset()
+		NamedRuleset(gameState.GameType)
 	gameState.ruleset = ruleset
 
 	// Initialize snake states as empty until we can ping the snake URLs
@@ -173,13 +174,22 @@ func (gameState *GameState) Initialize() error {
 }
 
 // Setup and run a full game.
-func (gameState *GameState) Run() {
+func (gameState *GameState) Run() error {
+	var gameOver bool
+	var err error
+
 	// Setup local state for snakes
-	gameState.snakeStates = gameState.buildSnakesFromOptions()
+	gameState.snakeStates, err = gameState.buildSnakesFromOptions()
+	if err != nil {
+		return fmt.Errorf("Error getting snake metadata: %w", err)
+	}
 
 	rand.Seed(gameState.Seed)
 
-	boardState := gameState.initializeBoardFromArgs()
+	gameOver, boardState, err := gameState.initializeBoardFromArgs()
+	if err != nil {
+		return fmt.Errorf("Error initializing board: %w", err)
+	}
 
 	gameExporter := GameExporter{
 		game:          gameState.createClientGame(),
@@ -209,7 +219,7 @@ func (gameState *GameState) Run() {
 	if gameState.ViewInBrowser {
 		serverURL, err := boardServer.Listen()
 		if err != nil {
-			log.ERROR.Fatalf("Error starting HTTP server: %v", err)
+			return fmt.Errorf("Error starting HTTP server: %w", err)
 		}
 		defer boardServer.Shutdown()
 		log.INFO.Printf("Board server listening on %s", serverURL)
@@ -233,13 +243,7 @@ func (gameState *GameState) Run() {
 		gameState.printState(boardState)
 	}
 
-	var endTime time.Time
+	// Export game first, if enabled, so that we capture the request for turn zero.
-	for v := false; !v; v, _ = gameState.ruleset.IsGameOver(boardState) {
-		if gameState.TurnDuration > 0 {
-			endTime = time.Now().Add(time.Duration(gameState.TurnDuration) * time.Millisecond)
-		}
-
-		// Export game first, if enabled, so that we save the board on turn zero
 	if exportGame {
 		// The output file was designed in a way so that (nearly) every entry is equivalent to a valid API request.
 		// This is meant to help unlock further development of tools such as replaying a saved game by simply copying each line and sending it as a POST request.
@@ -255,7 +259,21 @@ func (gameState *GameState) Run() {
 		}
 	}
 
-		boardState = gameState.createNextBoardState(boardState)
+	var endTime time.Time
+	for !gameOver {
+		if gameState.TurnDuration > 0 {
+			endTime = time.Now().Add(time.Duration(gameState.TurnDuration) * time.Millisecond)
+		}
+
+		gameOver, boardState, err = gameState.createNextBoardState(boardState)
+		if err != nil {
+			return fmt.Errorf("Error processing game: %w", err)
+		}
+
+		if gameOver {
+			// Stop processing here - because game over is detected at the start of the pipeline, nothing will have changed.
+			break
+		}
 
 		if gameState.ViewMap {
 			gameState.printMap(boardState)
@@ -274,9 +292,7 @@ func (gameState *GameState) Run() {
 		if gameState.ViewInBrowser {
 			boardServer.SendEvent(gameState.buildFrameEvent(boardState))
 		}
-	}
 
-	// Export final turn
 		if exportGame {
 			for _, snakeState := range gameState.snakeStates {
 				snakeRequest := gameState.getRequestBodyForSnake(boardState, snakeState)
@@ -284,6 +300,7 @@ func (gameState *GameState) Run() {
 				break
 			}
 		}
+	}
 
 	gameExporter.isDraw = false
 
@@ -320,24 +337,26 @@ func (gameState *GameState) Run() {
 	if exportGame {
 		lines, err := gameExporter.FlushToFile(gameState.outputFile)
 		if err != nil {
-			log.ERROR.Fatalf("Unable to export game. Reason: %v", err)
+			return fmt.Errorf("Unable to export game: %w", err)
 		}
 		log.INFO.Printf("Wrote %d lines to output file: %s", lines, gameState.OutputPath)
 	}
+
+	return nil
 }
 
-func (gameState *GameState) initializeBoardFromArgs() *rules.BoardState {
+func (gameState *GameState) initializeBoardFromArgs() (bool, *rules.BoardState, error) {
 	snakeIds := []string{}
 	for _, snakeState := range gameState.snakeStates {
 		snakeIds = append(snakeIds, snakeState.ID)
 	}
 	boardState, err := maps.SetupBoard(gameState.gameMap.ID(), gameState.ruleset.Settings(), gameState.Width, gameState.Height, snakeIds)
 	if err != nil {
-		log.ERROR.Fatalf("Error Initializing Board State: %v", err)
+		return false, nil, fmt.Errorf("Error initializing BoardState with map: %w", err)
 	}
-	boardState, err = gameState.ruleset.ModifyInitialBoardState(boardState)
+	gameOver, boardState, err := gameState.ruleset.Execute(boardState, nil)
 	if err != nil {
-		log.ERROR.Fatalf("Error Initializing Board State: %v", err)
+		return false, nil, fmt.Errorf("Error initializing BoardState with ruleset: %w", err)
 	}
 
 	for _, snakeState := range gameState.snakeStates {
@@ -351,12 +370,18 @@ func (gameState *GameState) initializeBoardFromArgs() *rules.BoardState {
 			log.WARN.Printf("Request to %v failed", u.String())
 		}
 	}
-	return boardState
+	return gameOver, boardState, nil
 }
 
-func (gameState *GameState) createNextBoardState(boardState *rules.BoardState) *rules.BoardState {
+func (gameState *GameState) createNextBoardState(boardState *rules.BoardState) (bool, *rules.BoardState, error) {
-	stateUpdates := make(chan SnakeState, len(gameState.snakeStates))
+	// apply PreUpdateBoard before making requests to snakes
+	boardState, err := maps.PreUpdateBoard(gameState.gameMap, boardState, gameState.ruleset.Settings())
+	if err != nil {
+		return false, boardState, fmt.Errorf("Error pre-updating board with game map: %w", err)
+	}
 
+	// get moves from snakes
+	stateUpdates := make(chan SnakeState, len(gameState.snakeStates))
 	if gameState.Sequential {
 		for _, snakeState := range gameState.snakeStates {
 			for _, snake := range boardState.Snakes {
@@ -393,19 +418,20 @@ func (gameState *GameState) createNextBoardState(boardState *rules.BoardState) *
 		moves = append(moves, rules.SnakeMove{ID: snakeState.ID, Move: snakeState.LastMove})
 	}
 
-	boardState, err := gameState.ruleset.CreateNextBoardState(boardState, moves)
+	gameOver, boardState, err := gameState.ruleset.Execute(boardState, moves)
 	if err != nil {
-		log.ERROR.Fatalf("Error producing next board state: %v", err)
+		return false, boardState, fmt.Errorf("Error updating board state from ruleset: %w", err)
 	}
 
-	boardState, err = maps.UpdateBoard(gameState.gameMap.ID(), boardState, gameState.ruleset.Settings())
+	// apply PostUpdateBoard after ruleset operates on snake moves
+	boardState, err = maps.PostUpdateBoard(gameState.gameMap, boardState, gameState.ruleset.Settings())
 	if err != nil {
-		log.ERROR.Fatalf("Error updating board with game map: %v", err)
+		return false, boardState, fmt.Errorf("Error post-updating board with game map: %w", err)
 	}
 
 	boardState.Turn += 1
 
-	return boardState
+	return gameOver, boardState, nil
 }
 
 func (gameState *GameState) getSnakeUpdate(boardState *rules.BoardState, snakeState SnakeState) SnakeState {
@@ -522,13 +548,13 @@ func (gameState *GameState) createClientGame() client.Game {
 		Ruleset: client.Ruleset{
 			Name:     gameState.ruleset.Name(),
 			Version:  "cli", // TODO: Use GitHub Release Version
-			Settings: gameState.ruleset.Settings(),
+			Settings: client.ConvertRulesetSettings(gameState.ruleset.Settings()),
 		},
 		Map: gameState.gameMap.ID(),
 	}
 }
 
-func (gameState *GameState) buildSnakesFromOptions() map[string]SnakeState {
+func (gameState *GameState) buildSnakesFromOptions() (map[string]SnakeState, error) {
 	bodyChars := []rune{'■', '⌀', '●', '☻', '◘', '☺', '□', '⍟'}
 	var numSnakes int
 	snakes := map[string]SnakeState{}
@@ -560,11 +586,11 @@ func (gameState *GameState) buildSnakesFromOptions() map[string]SnakeState {
 		if i < numURLs {
 			u, err := url.ParseRequestURI(gameState.URLs[i])
 			if err != nil {
-				log.ERROR.Fatalf("URL %v is not valid: %v", gameState.URLs[i], err)
+				return nil, fmt.Errorf("URL %v is not valid: %w", gameState.URLs[i], err)
 			}
 			snakeURL = u.String()
 		} else {
-			log.ERROR.Fatalf("URL for name %v is missing", gameState.Names[i])
+			return nil, fmt.Errorf("URL for name %v is missing", gameState.Names[i])
 		}
 
 		snakeState := SnakeState{
@@ -573,25 +599,25 @@ func (gameState *GameState) buildSnakesFromOptions() map[string]SnakeState {
 		var snakeErr error
 		res, _, err := gameState.httpClient.Get(snakeURL)
 		if err != nil {
-			log.ERROR.Fatalf("Snake metadata request to %v failed: %v", snakeURL, err)
+			return nil, fmt.Errorf("Snake metadata request to %v failed: %w", snakeURL, err)
 		}
 
 		snakeState.StatusCode = res.StatusCode
 
 		if res.Body == nil {
-			log.ERROR.Fatalf("Empty response body from snake metadata URL: %v", snakeURL)
+			return nil, fmt.Errorf("Empty response body from snake metadata URL: %v", snakeURL)
 		}
 
 		defer res.Body.Close()
 		body, readErr := ioutil.ReadAll(res.Body)
 		if readErr != nil {
-			log.ERROR.Fatalf("Error reading from snake metadata URL %v: %v", snakeURL, readErr)
+			return nil, fmt.Errorf("Error reading from snake metadata URL %v: %w", snakeURL, readErr)
 		}
 
 		pingResponse := client.SnakeMetadataResponse{}
 		jsonErr := json.Unmarshal(body, &pingResponse)
 		if jsonErr != nil {
-			log.ERROR.Fatalf("Failed to parse response from %v: %v", snakeURL, jsonErr)
+			return nil, fmt.Errorf("Failed to parse response from %v: %w", snakeURL, jsonErr)
 		}
 
 		snakeState.Head = pingResponse.Head
@@ -608,7 +634,7 @@ func (gameState *GameState) buildSnakesFromOptions() map[string]SnakeState {
 
 		log.INFO.Printf("Snake ID: %v URL: %v, Name: \"%v\"", snakeState.ID, snakeURL, snakeState.Name)
 	}
-	return snakes
+	return snakes, nil
 }
 
 func (gameState *GameState) printState(boardState *rules.BoardState) {
@@ -762,7 +788,8 @@ func (gameState *GameState) buildFrameEvent(boardState *rules.BoardState) board.
 func serialiseSnakeRequest(snakeRequest client.SnakeRequest) []byte {
 	requestJSON, err := json.Marshal(snakeRequest)
 	if err != nil {
-		log.ERROR.Fatalf("Error marshalling JSON from State: %v", err)
+		// This is likely to be a programming error like a unsupported type or cyclical reference
+		log.ERROR.Panicf("Error marshalling JSON from State: %v", err)
 	}
 	return requestJSON
 }

cli/commands/play_test.go

@@ -45,11 +45,10 @@ func buildDefaultGameState() *GameState {
 func TestGetIndividualBoardStateForSnake(t *testing.T) {
 	s1 := rules.Snake{ID: "one", Body: []rules.Point{{X: 3, Y: 3}}}
 	s2 := rules.Snake{ID: "two", Body: []rules.Point{{X: 4, Y: 3}}}
-	state := &rules.BoardState{
+	state := rules.NewBoardState(11, 11).
-		Height: 11,
+		WithSnakes(
-		Width:  11,
+			[]rules.Snake{s1, s2},
-		Snakes: []rules.Snake{s1, s2},
+		)
-	}
 	s1State := SnakeState{
 		ID:    "one",
 		Name:  "ONE",
@@ -85,11 +84,8 @@ func TestGetIndividualBoardStateForSnake(t *testing.T) {
 func TestSettingsRequestSerialization(t *testing.T) {
 	s1 := rules.Snake{ID: "one", Body: []rules.Point{{X: 3, Y: 3}}}
 	s2 := rules.Snake{ID: "two", Body: []rules.Point{{X: 4, Y: 3}}}
-	state := &rules.BoardState{
+	state := rules.NewBoardState(11, 11).
-		Height: 11,
+		WithSnakes([]rules.Snake{s1, s2})
-		Width:  11,
-		Snakes: []rules.Snake{s1, s2},
-	}
 	s1State := SnakeState{
 		ID:    "one",
 		Name:  "ONE",
@@ -255,12 +251,11 @@ func TestBuildFrameEvent(t *testing.T) {
 		},
 		{
 			name: "snake fields",
-			boardState: &rules.BoardState{
+			boardState: rules.NewBoardState(19, 25).
-				Turn:   99,
+				WithTurn(99).
-				Height: 19,
+				WithFood([]rules.Point{{X: 9, Y: 4}}).
-				Width:  25,
+				WithHazards([]rules.Point{{X: 8, Y: 6}}).
-				Food:   []rules.Point{{X: 9, Y: 4}},
+				WithSnakes([]rules.Snake{
-				Snakes: []rules.Snake{
 					{
 						ID: "1",
 						Body: []rules.Point{
@@ -273,9 +268,7 @@ func TestBuildFrameEvent(t *testing.T) {
 						EliminatedOnTurn: 45,
 						EliminatedBy:     "1",
 					},
-				},
+				}),
-				Hazards: []rules.Point{{X: 8, Y: 6}},
-			},
 			snakeStates: map[string]SnakeState{
 				"1": {
 					URL:        "http://example.com",
@@ -326,18 +319,15 @@ func TestBuildFrameEvent(t *testing.T) {
 		},
 		{
 			name: "snake errors",
-			boardState: &rules.BoardState{
+			boardState: rules.NewBoardState(19, 25).
-				Height: 19,
+				WithSnakes([]rules.Snake{
-				Width:  25,
-				Snakes: []rules.Snake{
 					{
 						ID: "bad_status",
 					},
 					{
 						ID: "connection_error",
 					},
-				},
+				}),
-			},
 			snakeStates: map[string]SnakeState{
 				"bad_status": {
 					StatusCode: 504,
@@ -366,6 +356,8 @@ func TestBuildFrameEvent(t *testing.T) {
 							Error:      "0:Error communicating with server",
 						},
 					},
+					Food:    []rules.Point{},
+					Hazards: []rules.Point{},
 				},
 			},
 		},
@@ -384,11 +376,7 @@ func TestBuildFrameEvent(t *testing.T) {
 func TestGetMoveForSnake(t *testing.T) {
 	s1 := rules.Snake{ID: "one", Body: []rules.Point{{X: 3, Y: 3}}}
 	s2 := rules.Snake{ID: "two", Body: []rules.Point{{X: 4, Y: 3}}}
-	boardState := &rules.BoardState{
+	boardState := rules.NewBoardState(11, 11).WithSnakes([]rules.Snake{s1, s2})
-		Height: 11,
-		Width:  11,
-		Snakes: []rules.Snake{s1, s2},
-	}
 
 	tests := []struct {
 		name            string
@@ -530,11 +518,7 @@ func TestGetMoveForSnake(t *testing.T) {
 
 func TestCreateNextBoardState(t *testing.T) {
 	s1 := rules.Snake{ID: "one", Body: []rules.Point{{X: 3, Y: 3}}}
-	boardState := &rules.BoardState{
+	boardState := rules.NewBoardState(11, 11).WithSnakes([]rules.Snake{s1})
-		Height: 11,
-		Width:  11,
-		Snakes: []rules.Snake{s1},
-	}
 	snakeState := SnakeState{
 		ID:  s1.ID,
 		URL: "http://example.com",
@@ -549,7 +533,9 @@ func TestCreateNextBoardState(t *testing.T) {
 			gameState.snakeStates = map[string]SnakeState{s1.ID: snakeState}
 			gameState.httpClient = stubHTTPClient{nil, 200, func(_ string) string { return `{"move": "right"}` }, 54 * time.Millisecond}
 
-			nextBoardState := gameState.createNextBoardState(boardState)
+			gameOver, nextBoardState, err := gameState.createNextBoardState(boardState)
+			require.NoError(t, err)
+			require.False(t, gameOver)
 			snakeState = gameState.snakeStates[s1.ID]
 
 			require.NotNil(t, nextBoardState)
@@ -593,16 +579,18 @@ func TestOutputFile(t *testing.T) {
 	outputFile := new(closableBuffer)
 	gameState.outputFile = outputFile
 
-	gameState.ruleset = StubRuleset{maxTurns: 1, settings: rules.Settings{
+	gameState.ruleset = StubRuleset{
-		FoodSpawnChance:     1,
+		maxTurns: 1,
-		MinimumFood:         2,
+		settings: rules.NewSettings(map[string]string{
-		HazardDamagePerTurn: 3,
+			rules.ParamFoodSpawnChance:     "1",
-		RoyaleSettings: rules.RoyaleSettings{
+			rules.ParamMinimumFood:         "2",
-			ShrinkEveryNTurns: 4,
+			rules.ParamHazardDamagePerTurn: "3",
-		},
+			rules.ParamShrinkEveryNTurns:   "4",
-	}}
+		}),
+	}
 
-	gameState.Run()
+	err = gameState.Run()
+	require.NoError(t, err)
 
 	lines := strings.Split(outputFile.String(), "\n")
 	require.Len(t, lines, 5)
@@ -626,14 +614,8 @@ type StubRuleset struct {
 
 func (ruleset StubRuleset) Name() string             { return "standard" }
 func (ruleset StubRuleset) Settings() rules.Settings { return ruleset.settings }
-func (ruleset StubRuleset) ModifyInitialBoardState(initialState *rules.BoardState) (*rules.BoardState, error) {
+func (ruleset StubRuleset) Execute(prevState *rules.BoardState, moves []rules.SnakeMove) (bool, *rules.BoardState, error) {
-	return initialState, nil
+	return prevState.Turn >= ruleset.maxTurns, prevState, nil
-}
-func (ruleset StubRuleset) CreateNextBoardState(prevState *rules.BoardState, moves []rules.SnakeMove) (*rules.BoardState, error) {
-	return prevState, nil
-}
-func (ruleset StubRuleset) IsGameOver(state *rules.BoardState) (bool, error) {
-	return state.Turn >= ruleset.maxTurns, nil
 }
 
 type stubHTTPClient struct {

client/fixtures_test.go

@@ -9,7 +9,7 @@ func exampleSnakeRequest() SnakeRequest {
 			Ruleset: Ruleset{
 				Name:     "test-ruleset-name",
 				Version:  "cli",
-				Settings: exampleRulesetSettings,
+				Settings: ConvertRulesetSettings(exampleRulesetSettings),
 			},
 			Timeout: 33,
 			Source:  "league",
@@ -75,21 +75,9 @@ func exampleSnakeRequest() SnakeRequest {
 	}
 }
 
-var exampleRulesetSettings = rules.Settings{
+var exampleRulesetSettings = rules.NewSettings(map[string]string{
-	FoodSpawnChance:     10,
+	rules.ParamFoodSpawnChance:     "10",
-	MinimumFood:         20,
+	rules.ParamMinimumFood:         "20",
-	HazardDamagePerTurn: 30,
+	rules.ParamHazardDamagePerTurn: "30",
-	HazardMap:           "hz_spiral",
+	rules.ParamShrinkEveryNTurns:   "40",
-	HazardMapAuthor:     "altersaddle",
+})
-
-	RoyaleSettings: rules.RoyaleSettings{
-		ShrinkEveryNTurns: 40,
-	},
-
-	SquadSettings: rules.SquadSettings{
-		AllowBodyCollisions: true,
-		SharedElimination:   true,
-		SharedHealth:        true,
-		SharedLength:        true,
-	},
-}

client/models.go

@@ -51,17 +51,45 @@ type Customizations struct {
 type Ruleset struct {
 	Name     string          `json:"name"`
 	Version  string          `json:"version"`
-	Settings rules.Settings `json:"settings"`
+	Settings RulesetSettings `json:"settings"`
 }
 
-// RulesetSettings is deprecated: use rules.Settings instead
+// RulesetSettings contains a static collection of a few settings that are exposed through the API.
-type RulesetSettings rules.Settings
+type RulesetSettings struct {
+	FoodSpawnChance     int            `json:"foodSpawnChance"`
+	MinimumFood         int            `json:"minimumFood"`
+	HazardDamagePerTurn int            `json:"hazardDamagePerTurn"`
+	HazardMap           string         `json:"hazardMap"`       // Deprecated, replaced by Game.Map
+	HazardMapAuthor     string         `json:"hazardMapAuthor"` // Deprecated, no planned replacement
+	RoyaleSettings      RoyaleSettings `json:"royale"`
+	SquadSettings       SquadSettings  `json:"squad"` // Deprecated, provided with default fields for API compatibility
+}
 
-// RoyaleSettings is deprecated: use rules.RoyaleSettings instead
+// RoyaleSettings contains settings that are specific to the "royale" game mode
-type RoyaleSettings rules.RoyaleSettings
+type RoyaleSettings struct {
+	ShrinkEveryNTurns int `json:"shrinkEveryNTurns"`
+}
 
-// SquadSettings is deprecated: use rules.SquadSettings instead
+// SquadSettings contains settings that are specific to the "squad" game mode
-type SquadSettings rules.SquadSettings
+type SquadSettings struct {
+	AllowBodyCollisions bool `json:"allowBodyCollisions"`
+	SharedElimination   bool `json:"sharedElimination"`
+	SharedHealth        bool `json:"sharedHealth"`
+	SharedLength        bool `json:"sharedLength"`
+}
+
+// Converts a rules.Settings (which can contain arbitrary settings) into the static RulesetSettings used in the client API.
+func ConvertRulesetSettings(settings rules.Settings) RulesetSettings {
+	return RulesetSettings{
+		FoodSpawnChance:     settings.Int(rules.ParamFoodSpawnChance, 0),
+		MinimumFood:         settings.Int(rules.ParamMinimumFood, 0),
+		HazardDamagePerTurn: settings.Int(rules.ParamHazardDamagePerTurn, 0),
+		RoyaleSettings: RoyaleSettings{
+			ShrinkEveryNTurns: settings.Int(rules.ParamShrinkEveryNTurns, 0),
+		},
+		SquadSettings: SquadSettings{},
+	}
+}
 
 // Coord represents a point on the board
 type Coord struct {

client/models_test.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"testing"
 
-	"github.com/BattlesnakeOfficial/rules"
 	"github.com/BattlesnakeOfficial/rules/test"
 	"github.com/stretchr/testify/require"
 )
@@ -19,7 +18,7 @@ func TestBuildSnakeRequestJSON(t *testing.T) {
 
 func TestBuildSnakeRequestJSONEmptyRulesetSettings(t *testing.T) {
 	snakeRequest := exampleSnakeRequest()
-	snakeRequest.Game.Ruleset.Settings = rules.Settings{}
+	snakeRequest.Game.Ruleset.Settings = RulesetSettings{}
 	data, err := json.MarshalIndent(snakeRequest, "", "  ")
 	require.NoError(t, err)
 

client/testdata/snake_request.json

@@ -8,16 +8,16 @@
         "foodSpawnChance": 10,
         "minimumFood": 20,
         "hazardDamagePerTurn": 30,
-        "hazardMap": "hz_spiral",
+        "hazardMap": "",
-        "hazardMapAuthor": "altersaddle",
+        "hazardMapAuthor": "",
         "royale": {
           "shrinkEveryNTurns": 40
         },
         "squad": {
-          "allowBodyCollisions": true,
+          "allowBodyCollisions": false,
-          "sharedElimination": true,
+          "sharedElimination": false,
-          "sharedHealth": true,
+          "sharedHealth": false,
-          "sharedLength": true
+          "sharedLength": false
         }
       }
     },

constrictor.go

@@ -22,31 +22,6 @@ var wrappedConstrictorRulesetStages = []string{
 	StageModifySnakesAlwaysGrow,
 }
 
-type ConstrictorRuleset struct {
-	StandardRuleset
-}
-
-func (r *ConstrictorRuleset) Name() string { return GameTypeConstrictor }
-
-func (r ConstrictorRuleset) Execute(bs *BoardState, s Settings, sm []SnakeMove) (bool, *BoardState, error) {
-	return NewPipeline(constrictorRulesetStages...).Execute(bs, s, sm)
-}
-
-func (r *ConstrictorRuleset) ModifyInitialBoardState(initialBoardState *BoardState) (*BoardState, error) {
-	_, nextState, err := r.Execute(initialBoardState, r.Settings(), nil)
-	return nextState, err
-}
-
-func (r *ConstrictorRuleset) CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
-	_, nextState, err := r.Execute(prevState, r.Settings(), moves)
-
-	return nextState, err
-}
-
-func (r *ConstrictorRuleset) IsGameOver(b *BoardState) (bool, error) {
-	return GameOverStandard(b, r.Settings(), nil)
-}
-
 func RemoveFoodConstrictor(b *BoardState, settings Settings, moves []SnakeMove) (bool, error) {
 	// Remove all food from the board
 	b.Food = []Point{}

constrictor_test.go

@@ -4,10 +4,6 @@ import (
 	"testing"
 )
 
-func TestConstrictorRulesetInterface(t *testing.T) {
-	var _ Ruleset = (*ConstrictorRuleset)(nil)
-}
-
 // Test that two equal snakes collide and both get eliminated
 // also checks:
 //	- food removed
@@ -21,16 +17,16 @@ var constrictorMoveAndCollideMAD = gameTestCase{
 		Snakes: []Snake{
 			{
 				ID:     "one",
-				Body:   []Point{{1, 1}, {2, 1}},
+				Body:   []Point{{X: 1, Y: 1}, {X: 2, Y: 1}},
 				Health: 99,
 			},
 			{
 				ID:     "two",
-				Body:   []Point{{1, 2}, {2, 2}},
+				Body:   []Point{{X: 1, Y: 2}, {X: 2, Y: 2}},
 				Health: 99,
 			},
 		},
-		Food:    []Point{{10, 10}, {9, 9}, {8, 8}},
+		Food:    []Point{{X: 10, Y: 10}, {X: 9, Y: 9}, {X: 8, Y: 8}},
 		Hazards: []Point{},
 	},
 	[]SnakeMove{
@@ -44,7 +40,7 @@ var constrictorMoveAndCollideMAD = gameTestCase{
 		Snakes: []Snake{
 			{
 				ID:               "one",
-				Body:             []Point{{1, 2}, {1, 1}, {1, 1}},
+				Body:             []Point{{X: 1, Y: 2}, {X: 1, Y: 1}, {X: 1, Y: 1}},
 				Health:           100,
 				EliminatedCause:  EliminatedByCollision,
 				EliminatedBy:     "two",
@@ -52,7 +48,7 @@ var constrictorMoveAndCollideMAD = gameTestCase{
 			},
 			{
 				ID:               "two",
-				Body:             []Point{{1, 1}, {1, 2}, {1, 2}},
+				Body:             []Point{{X: 1, Y: 1}, {X: 1, Y: 2}, {X: 1, Y: 2}},
 				Health:           100,
 				EliminatedCause:  EliminatedByCollision,
 				EliminatedBy:     "one",
@@ -70,15 +66,11 @@ func TestConstrictorCreateNextBoardState(t *testing.T) {
 		standardCaseErrZeroLengthSnake,
 		constrictorMoveAndCollideMAD,
 	}
-	rb := NewRulesetBuilder().WithParams(map[string]string{
+	r := NewRulesetBuilder().NamedRuleset(GameTypeConstrictor)
-		ParamGameType: GameTypeConstrictor,
-	})
-	r := ConstrictorRuleset{}
 	for _, gc := range cases {
-		gc.requireValidNextState(t, &r)
+		// test a RulesBuilder constructed instance
-		// also test a RulesBuilder constructed instance
+		gc.requireValidNextState(t, r)
-		gc.requireValidNextState(t, rb.Ruleset())
 		// also test a pipeline with the same settings
-		gc.requireValidNextState(t, rb.PipelineRuleset(GameTypeConstrictor, NewPipeline(constrictorRulesetStages...)))
+		gc.requireValidNextState(t, NewRulesetBuilder().PipelineRuleset(GameTypeConstrictor, NewPipeline(constrictorRulesetStages...)))
 	}
 }

maps/arcade_maze.go

@@ -63,7 +63,7 @@ func (m ArcadeMazeMap) SetupBoard(initialBoardState *rules.BoardState, settings
 		editor.AddHazard(hazard)
 	}
 
-	if settings.MinimumFood > 0 {
+	if settings.Int(rules.ParamMinimumFood, 0) > 0 {
 		// Add food in center
 		editor.AddFood(rules.Point{X: 9, Y: 11})
 	}
@@ -71,11 +71,16 @@ func (m ArcadeMazeMap) SetupBoard(initialBoardState *rules.BoardState, settings
 	return nil
 }
 
-func (m ArcadeMazeMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m ArcadeMazeMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m ArcadeMazeMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	rand := settings.GetRand(lastBoardState.Turn)
 
 	// Respect FoodSpawnChance setting
-	if settings.FoodSpawnChance == 0 || rand.Intn(100) > settings.FoodSpawnChance {
+	foodSpawnChance := settings.Int(rules.ParamFoodSpawnChance, 0)
+	if foodSpawnChance == 0 || rand.Intn(100) > foodSpawnChance {
 		return nil
 	}
 

maps/castle_wall.go

@@ -136,7 +136,11 @@ func (m CastleWallMediumHazardsMap) SetupBoard(initialBoardState *rules.BoardSta
 	return setupCastleWallBoard(m.Meta().MaxPlayers, startPositions, castleWallMediumHazards, initialBoardState, settings, editor)
 }
 
-func (m CastleWallMediumHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m CastleWallMediumHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m CastleWallMediumHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	maxFood := 2
 	return updateCastleWallBoard(maxFood, castleWallMediumFood, lastBoardState, settings, editor)
 }
@@ -228,7 +232,11 @@ func (m CastleWallLargeHazardsMap) SetupBoard(initialBoardState *rules.BoardStat
 	return setupCastleWallBoard(m.Meta().MaxPlayers, startPositions, castleWallLargeHazards, initialBoardState, settings, editor)
 }
 
-func (m CastleWallLargeHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m CastleWallLargeHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m CastleWallLargeHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	maxFood := 2
 	return updateCastleWallBoard(maxFood, castleWallLargeFood, lastBoardState, settings, editor)
 }
@@ -420,7 +428,11 @@ func (m CastleWallExtraLargeHazardsMap) SetupBoard(initialBoardState *rules.Boar
 	return setupCastleWallBoard(m.Meta().MaxPlayers, startPositions, castleWallExtraLargeHazards, initialBoardState, settings, editor)
 }
 
-func (m CastleWallExtraLargeHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m CastleWallExtraLargeHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m CastleWallExtraLargeHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	maxFood := 4
 	return updateCastleWallBoard(maxFood, castleWallExtraLargeFood, lastBoardState, settings, editor)
 }

maps/empty.go

@@ -53,6 +53,10 @@ func (m EmptyMap) SetupBoard(initialBoardState *rules.BoardState, settings rules
 	return nil
 }
 
-func (m EmptyMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m EmptyMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m EmptyMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	return nil
 }

maps/empty_test.go

@@ -28,55 +28,28 @@ func TestEmptyMapSetupBoard(t *testing.T) {
 			"empty 7x7",
 			rules.NewBoardState(7, 7),
 			rules.MinRand,
-			&rules.BoardState{
+			rules.NewBoardState(7, 7),
-				Width:   7,
-				Height:  7,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			nil,
 		},
 		{
 			"not enough room for snakes 7x7",
-			&rules.BoardState{
+			rules.NewBoardState(7, 7).WithSnakes(generateSnakes(17)),
-				Width:   7,
-				Height:  7,
-				Snakes:  generateSnakes(17),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			rules.MinRand,
 			nil,
 			rules.ErrorTooManySnakes,
 		},
 		{
 			"not enough room for snakes 5x5",
-			&rules.BoardState{
+			rules.NewBoardState(5, 5).WithSnakes(generateSnakes(14)),
-				Width:   5,
-				Height:  5,
-				Snakes:  generateSnakes(14),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			rules.MinRand,
 			nil,
 			rules.ErrorTooManySnakes,
 		},
 		{
 			"full 11x11 min",
-			&rules.BoardState{
+			rules.NewBoardState(11, 11).WithSnakes(generateSnakes(8)),
-				Width:   11,
-				Height:  11,
-				Snakes:  generateSnakes(8),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			rules.MinRand,
-			&rules.BoardState{
+			rules.NewBoardState(11, 11).WithSnakes([]rules.Snake{
-				Width:  11,
-				Height: 11,
-				Snakes: []rules.Snake{
 				{ID: "1", Body: []rules.Point{{X: 1, Y: 1}, {X: 1, Y: 1}, {X: 1, Y: 1}}, Health: 100},
 				{ID: "2", Body: []rules.Point{{X: 1, Y: 9}, {X: 1, Y: 9}, {X: 1, Y: 9}}, Health: 100},
 				{ID: "3", Body: []rules.Point{{X: 9, Y: 1}, {X: 9, Y: 1}, {X: 9, Y: 1}}, Health: 100},
@@ -85,26 +58,14 @@ func TestEmptyMapSetupBoard(t *testing.T) {
 				{ID: "6", Body: []rules.Point{{X: 5, Y: 1}, {X: 5, Y: 1}, {X: 5, Y: 1}}, Health: 100},
 				{ID: "7", Body: []rules.Point{{X: 5, Y: 9}, {X: 5, Y: 9}, {X: 5, Y: 9}}, Health: 100},
 				{ID: "8", Body: []rules.Point{{X: 9, Y: 5}, {X: 9, Y: 5}, {X: 9, Y: 5}}, Health: 100},
-				},
+			}),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			nil,
 		},
 		{
 			"full 11x11 max",
-			&rules.BoardState{
+			rules.NewBoardState(11, 11).WithSnakes(generateSnakes(8)),
-				Width:   11,
-				Height:  11,
-				Snakes:  generateSnakes(8),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			rules.MaxRand,
-			&rules.BoardState{
+			rules.NewBoardState(11, 11).WithSnakes([]rules.Snake{
-				Width:  11,
-				Height: 11,
-				Snakes: []rules.Snake{
 				{ID: "1", Body: []rules.Point{{X: 5, Y: 1}, {X: 5, Y: 1}, {X: 5, Y: 1}}, Health: 100},
 				{ID: "2", Body: []rules.Point{{X: 5, Y: 9}, {X: 5, Y: 9}, {X: 5, Y: 9}}, Health: 100},
 				{ID: "3", Body: []rules.Point{{X: 9, Y: 5}, {X: 9, Y: 5}, {X: 9, Y: 5}}, Health: 100},
@@ -113,10 +74,7 @@ func TestEmptyMapSetupBoard(t *testing.T) {
 				{ID: "6", Body: []rules.Point{{X: 9, Y: 1}, {X: 9, Y: 1}, {X: 9, Y: 1}}, Health: 100},
 				{ID: "7", Body: []rules.Point{{X: 9, Y: 9}, {X: 9, Y: 9}, {X: 9, Y: 9}}, Health: 100},
 				{ID: "8", Body: []rules.Point{{X: 1, Y: 1}, {X: 1, Y: 1}, {X: 1, Y: 1}}, Health: 100},
-				},
+			}),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			nil,
 		},
 	}
@@ -139,27 +97,13 @@ func TestEmptyMapSetupBoard(t *testing.T) {
 
 func TestEmptyMapUpdateBoard(t *testing.T) {
 	m := maps.EmptyMap{}
-	initialBoardState := &rules.BoardState{
+	initialBoardState := rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 0}})
-		Width:   2,
+	settings := rules.NewSettingsWithParams(rules.ParamFoodSpawnChance, "50", rules.ParamMinimumFood, "2").WithRand(rules.MaxRand)
-		Height:  2,
-		Snakes:  []rules.Snake{},
-		Food:    []rules.Point{{X: 0, Y: 0}},
-		Hazards: []rules.Point{},
-	}
-	settings := rules.Settings{
-		FoodSpawnChance: 50,
-		MinimumFood:     2,
-	}.WithRand(rules.MaxRand)
 	nextBoardState := initialBoardState.Clone()
 
-	err := m.UpdateBoard(initialBoardState.Clone(), settings, maps.NewBoardStateEditor(nextBoardState))
+	err := m.PostUpdateBoard(initialBoardState.Clone(), settings, maps.NewBoardStateEditor(nextBoardState))
 
 	require.NoError(t, err)
-	require.Equal(t, &rules.BoardState{
+	expectedBoardState := rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 0}})
-		Width:   2,
+	require.Equal(t, expectedBoardState, nextBoardState)
-		Height:  2,
-		Snakes:  []rules.Snake{},
-		Food:    []rules.Point{{X: 0, Y: 0}},
-		Hazards: []rules.Point{},
-	}, nextBoardState)
 }

maps/game_map.go

@@ -24,8 +24,21 @@ type GameMap interface {
 	// Called to generate a new board. The map is responsible for placing all snakes, food, and hazards.
 	SetupBoard(initialBoardState *rules.BoardState, settings rules.Settings, editor Editor) error
 
-	// Called every turn to optionally update the board.
+	// Called every turn to optionally update the board before the board is sent to snakes to get their moves.
-	UpdateBoard(previousBoardState *rules.BoardState, settings rules.Settings, editor Editor) error
+	// Changes made here will be seen by snakes before before making their moves, but users in the
+	// browser will see the changes at the same time as the snakes' moves.
+	//
+	// State that is stored in the map by this method will be visible to the PostUpdateBoard method
+	// later in the same turn, but will not nessecarily be available when processing later turns.
+	//
+	// Disclaimer: Unless you have a specific usecase like moving hazards or storing intermediate state,
+	// PostUpdateBoard is probably the better function to use.
+	PreUpdateBoard(previousBoardState *rules.BoardState, settings rules.Settings, editor Editor) error
+
+	// Called every turn to optionally update the board after all other rules have been applied.
+	// Changes made here will be seen by both snakes and users in the browser, before before snakes
+	// make their next moves.
+	PostUpdateBoard(previousBoardState *rules.BoardState, settings rules.Settings, editor Editor) error
 }
 
 type Metadata struct {
@@ -166,6 +179,12 @@ type Editor interface {
 	// Note: the body values in the return value are a copy and modifying them won't affect the board.
 	SnakeBodies() map[string][]rules.Point
 
+	// Get an editable reference to the BoardState's GameState field
+	GameState() map[string]string
+
+	// Get an editable reference to the BoardState's PointState field
+	PointState() map[rules.Point]int
+
 	// Given a list of Snakes and a list of head coordinates, randomly place
 	// the snakes on those coordinates, or return an error if placement of all
 	// Snakes is impossible.
@@ -270,6 +289,16 @@ func (editor *BoardStateEditor) SnakeBodies() map[string][]rules.Point {
 	return result
 }
 
+// Get an editable reference to the BoardState's GameState field
+func (editor *BoardStateEditor) GameState() map[string]string {
+	return editor.boardState.GameState
+}
+
+// Get an editable reference to the BoardState's PointState field
+func (editor *BoardStateEditor) PointState() map[rules.Point]int {
+	return editor.boardState.PointState
+}
+
 // Given a list of Snakes and a list of head coordinates, randomly place
 // the snakes on those coordinates, or return an error if placement of all
 // Snakes is impossible.

maps/game_map_test.go

@@ -135,18 +135,16 @@ func TestBoardStateEditor(t *testing.T) {
 	editor.PlaceSnake("existing_snake", []rules.Point{{X: 5, Y: 2}, {X: 5, Y: 1}, {X: 5, Y: 0}}, 99)
 	editor.PlaceSnake("new_snake", []rules.Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}}, 98)
 
-	require.Equal(t, &rules.BoardState{
+	expected := rules.NewBoardState(11, 11).
-		Width:  11,
+		WithFood([]rules.Point{
-		Height: 11,
-		Food: []rules.Point{
 			{X: 1, Y: 3},
 			{X: 3, Y: 7},
-		},
+		}).
-		Hazards: []rules.Point{
+		WithHazards([]rules.Point{
 			{X: 1, Y: 3},
 			{X: 3, Y: 7},
-		},
+		}).
-		Snakes: []rules.Snake{
+		WithSnakes([]rules.Snake{
 			{
 				ID:     "existing_snake",
 				Health: 99,
@@ -157,8 +155,8 @@ func TestBoardStateEditor(t *testing.T) {
 				Health: 98,
 				Body:   []rules.Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 1, Y: 1}},
 			},
-		},
+		})
-	}, boardState)
+	require.Equal(t, expected, boardState)
 
 	require.Equal(t, []rules.Point{
 		{X: 1, Y: 3},

maps/hazard_pits.go

@@ -97,8 +97,12 @@ func (m HazardPitsMap) SetupBoard(initialBoardState *rules.BoardState, settings
 	return nil
 }
 
-func (m HazardPitsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m HazardPitsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	err := StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return nil
+}
+
+func (m HazardPitsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	err := StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 	if err != nil {
 		return err
 	}
@@ -109,9 +113,10 @@ func (m HazardPitsMap) UpdateBoard(lastBoardState *rules.BoardState, settings ru
 	// Cycle 3 - 3 layers
 	// Cycle 4-6 - 4 layers of hazards
 
-	if lastBoardState.Turn%settings.RoyaleSettings.ShrinkEveryNTurns == 0 {
+	shrinkEveryNTurns := settings.Int(rules.ParamShrinkEveryNTurns, 0)
+	if lastBoardState.Turn%shrinkEveryNTurns == 0 {
 		// Is it time to update the hazards
-		layers := (lastBoardState.Turn / settings.RoyaleSettings.ShrinkEveryNTurns) % 7
+		layers := (lastBoardState.Turn / shrinkEveryNTurns) % 7
 		if layers > 4 {
 			layers = 4
 		}

maps/hazard_pits_test.go

@@ -38,7 +38,7 @@ func TestHazardPitsMap(t *testing.T) {
 
 	state = rules.NewBoardState(int(11), int(11))
 	m = maps.HazardPitsMap{}
-	settings.RoyaleSettings.ShrinkEveryNTurns = 1
+	settings = rules.NewSettingsWithParams(rules.ParamShrinkEveryNTurns, "1")
 	editor = maps.NewBoardStateEditor(state)
 	require.Empty(t, state.Hazards)
 	err = m.SetupBoard(state, settings, editor)
@@ -47,7 +47,7 @@ func TestHazardPitsMap(t *testing.T) {
 	// Verify the hazard progression through the turns
 	for i := 0; i < 16; i++ {
 		state.Turn = i
-		err = m.UpdateBoard(state, settings, editor)
+		err = m.PostUpdateBoard(state, settings, editor)
 		require.NoError(t, err)
 		if i == 1 {
 			require.Len(t, state.Hazards, 21)

maps/hazards.go

@@ -54,8 +54,12 @@ func (m InnerBorderHazardsMap) SetupBoard(lastBoardState *rules.BoardState, sett
 	return nil
 }
 
-func (m InnerBorderHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m InnerBorderHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	return StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return nil
+}
+
+func (m InnerBorderHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 }
 
 type ConcentricRingsHazardsMap struct{}
@@ -96,8 +100,12 @@ func (m ConcentricRingsHazardsMap) SetupBoard(lastBoardState *rules.BoardState,
 	return nil
 }
 
-func (m ConcentricRingsHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m ConcentricRingsHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	return StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return nil
+}
+
+func (m ConcentricRingsHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 }
 
 type ColumnsHazardsMap struct{}
@@ -135,8 +143,12 @@ func (m ColumnsHazardsMap) SetupBoard(lastBoardState *rules.BoardState, settings
 	return nil
 }
 
-func (m ColumnsHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m ColumnsHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	return StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return nil
+}
+
+func (m ColumnsHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 }
 
 type SpiralHazardsMap struct{}
@@ -163,8 +175,12 @@ func (m SpiralHazardsMap) SetupBoard(lastBoardState *rules.BoardState, settings
 	return (StandardMap{}).SetupBoard(lastBoardState, settings, editor)
 }
 
-func (m SpiralHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m SpiralHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	err := StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return nil
+}
+
+func (m SpiralHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	err := StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 	if err != nil {
 		return err
 	}
@@ -256,8 +272,12 @@ func (m ScatterFillMap) SetupBoard(lastBoardState *rules.BoardState, settings ru
 	return (StandardMap{}).SetupBoard(lastBoardState, settings, editor)
 }
 
-func (m ScatterFillMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m ScatterFillMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	err := StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return nil
+}
+
+func (m ScatterFillMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	err := StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 	if err != nil {
 		return err
 	}
@@ -308,8 +328,12 @@ func (m DirectionalExpandingBoxMap) SetupBoard(lastBoardState *rules.BoardState,
 	return (StandardMap{}).SetupBoard(lastBoardState, settings, editor)
 }
 
-func (m DirectionalExpandingBoxMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m DirectionalExpandingBoxMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	err := StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return nil
+}
+
+func (m DirectionalExpandingBoxMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	err := StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 	if err != nil {
 		return err
 	}
@@ -423,8 +447,12 @@ func (m ExpandingBoxMap) SetupBoard(lastBoardState *rules.BoardState, settings r
 	return (StandardMap{}).SetupBoard(lastBoardState, settings, editor)
 }
 
-func (m ExpandingBoxMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m ExpandingBoxMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	err := StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return nil
+}
+
+func (m ExpandingBoxMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	err := StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 	if err != nil {
 		return err
 	}
@@ -499,8 +527,12 @@ func (m ExpandingScatterMap) SetupBoard(lastBoardState *rules.BoardState, settin
 	return (StandardMap{}).SetupBoard(lastBoardState, settings, editor)
 }
 
-func (m ExpandingScatterMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m ExpandingScatterMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	err := StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return (StandardMap{}).PreUpdateBoard(lastBoardState, settings, editor)
+}
+
+func (m ExpandingScatterMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	err := StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 	if err != nil {
 		return err
 	}

maps/hazards_test.go

@@ -102,7 +102,7 @@ func TestSpiralHazardsMap(t *testing.T) {
 
 	for i := 0; i < 1000; i++ {
 		state.Turn = i
-		err = m.UpdateBoard(state, settings, editor)
+		err = m.PostUpdateBoard(state, settings, editor)
 		require.NoError(t, err)
 	}
 	require.NotEmpty(t, state.Hazards)
@@ -123,7 +123,7 @@ func TestScatterFillMap(t *testing.T) {
 	totalTurns := 11 * 11 * 2
 	for i := 0; i < totalTurns; i++ {
 		state.Turn = i
-		err = m.UpdateBoard(state, settings, editor)
+		err = m.PostUpdateBoard(state, settings, editor)
 		require.NoError(t, err)
 	}
 	require.NotEmpty(t, state.Hazards)
@@ -144,7 +144,7 @@ func TestDirectionalExpandingBoxMap(t *testing.T) {
 	totalTurns := 1000
 	for i := 0; i < totalTurns; i++ {
 		state.Turn = i
-		err = m.UpdateBoard(state, settings, editor)
+		err = m.PostUpdateBoard(state, settings, editor)
 		require.NoError(t, err)
 	}
 	require.NotEmpty(t, state.Hazards)
@@ -165,7 +165,7 @@ func TestExpandingBoxMap(t *testing.T) {
 	totalTurns := 1000
 	for i := 0; i < totalTurns; i++ {
 		state.Turn = i
-		err = m.UpdateBoard(state, settings, editor)
+		err = m.PostUpdateBoard(state, settings, editor)
 		require.NoError(t, err)
 	}
 	require.NotEmpty(t, state.Hazards)
@@ -186,7 +186,7 @@ func TestExpandingScatterMap(t *testing.T) {
 	totalTurns := 1000
 	for i := 0; i < totalTurns; i++ {
 		state.Turn = i
-		err = m.UpdateBoard(state, settings, editor)
+		err = m.PostUpdateBoard(state, settings, editor)
 		require.NoError(t, err)
 	}
 	require.NotEmpty(t, state.Hazards)

maps/healing_pools.go

@@ -50,12 +50,17 @@ func (m HealingPoolsMap) SetupBoard(initialBoardState *rules.BoardState, setting
 	return nil
 }
 
-func (m HealingPoolsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m HealingPoolsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	if err := (StandardMap{}).UpdateBoard(lastBoardState, settings, editor); err != nil {
+	return nil
+}
+
+func (m HealingPoolsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	if err := (StandardMap{}).PostUpdateBoard(lastBoardState, settings, editor); err != nil {
 		return err
 	}
 
-	if lastBoardState.Turn > 0 && settings.RoyaleSettings.ShrinkEveryNTurns > 0 && len(lastBoardState.Hazards) > 0 && lastBoardState.Turn%settings.RoyaleSettings.ShrinkEveryNTurns == 0 {
+	shrinkEveryNTurns := settings.Int(rules.ParamShrinkEveryNTurns, 0)
+	if lastBoardState.Turn > 0 && shrinkEveryNTurns > 0 && len(lastBoardState.Hazards) > 0 && lastBoardState.Turn%shrinkEveryNTurns == 0 {
 		// Attempt to remove a healing pool every ShrinkEveryNTurns until there are none remaining
 		i := rand.Intn(len(lastBoardState.Hazards))
 		editor.RemoveHazard(lastBoardState.Hazards[i])

maps/healing_pools_test.go

@@ -40,8 +40,8 @@ func TestHealingPoolsMap(t *testing.T) {
 		t.Run(fmt.Sprintf("%dx%d", tc.boardSize, tc.boardSize), func(t *testing.T) {
 			m := maps.HealingPoolsMap{}
 			state := rules.NewBoardState(tc.boardSize, tc.boardSize)
-			settings := rules.Settings{}
+			shrinkEveryNTurns := 10
-			settings.RoyaleSettings.ShrinkEveryNTurns = 10
+			settings := rules.NewSettingsWithParams(rules.ParamShrinkEveryNTurns, fmt.Sprint(shrinkEveryNTurns))
 
 			// ensure the hazards are added to the board at setup
 			editor := maps.NewBoardStateEditor(state)
@@ -56,10 +56,10 @@ func TestHealingPoolsMap(t *testing.T) {
 			}
 
 			// ensure the hazards are removed
-			totalTurns := settings.RoyaleSettings.ShrinkEveryNTurns*tc.expectedHazards + 1
+			totalTurns := shrinkEveryNTurns*tc.expectedHazards + 1
 			for i := 0; i < totalTurns; i++ {
 				state.Turn = i
-				err = m.UpdateBoard(state, settings, editor)
+				err = m.PostUpdateBoard(state, settings, editor)
 				require.NoError(t, err)
 			}
 

maps/helpers.go

@@ -25,17 +25,24 @@ func SetupBoard(mapID string, settings rules.Settings, width, height int, snakeI
 	return boardState, nil
 }
 
-//  UpdateBoard is a shortcut for looking up a map by ID and updating an existing board state with it.
+// PreUpdateBoard updates a board state with a map.
-func UpdateBoard(mapID string, previousBoardState *rules.BoardState, settings rules.Settings) (*rules.BoardState, error) {
+func PreUpdateBoard(gameMap GameMap, previousBoardState *rules.BoardState, settings rules.Settings) (*rules.BoardState, error) {
-	gameMap, err := GetMap(mapID)
+	nextBoardState := previousBoardState.Clone()
+	editor := NewBoardStateEditor(nextBoardState)
+
+	err := gameMap.PreUpdateBoard(previousBoardState, settings, editor)
 	if err != nil {
 		return nil, err
 	}
 
+	return nextBoardState, nil
+}
+
+func PostUpdateBoard(gameMap GameMap, previousBoardState *rules.BoardState, settings rules.Settings) (*rules.BoardState, error) {
 	nextBoardState := previousBoardState.Clone()
 	editor := NewBoardStateEditor(nextBoardState)
 
-	err = gameMap.UpdateBoard(previousBoardState, settings, editor)
+	err := gameMap.PostUpdateBoard(previousBoardState, settings, editor)
 	if err != nil {
 		return nil, err
 	}
@@ -77,7 +84,11 @@ func (m StubMap) SetupBoard(initialBoardState *rules.BoardState, settings rules.
 	return nil
 }
 
-func (m StubMap) UpdateBoard(previousBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m StubMap) PreUpdateBoard(previousBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m StubMap) PostUpdateBoard(previousBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	if m.Error != nil {
 		return m.Error
 	}

maps/helpers_test.go

@@ -82,11 +82,10 @@ func TestUpdateBoard(t *testing.T) {
 		},
 	}
 
-	previousBoardState := &rules.BoardState{
+	previousBoardState := rules.NewBoardState(5, 5).
-		Turn:    0,
+		WithFood([]rules.Point{{X: 0, Y: 1}}).
-		Food:    []rules.Point{{X: 0, Y: 1}},
+		WithHazards([]rules.Point{{X: 3, Y: 4}}).
-		Hazards: []rules.Point{{X: 3, Y: 4}},
+		WithSnakes([]rules.Snake{
-		Snakes: []rules.Snake{
 			{
 				ID:     "1",
 				Health: 100,
@@ -96,11 +95,9 @@ func TestUpdateBoard(t *testing.T) {
 					{X: 6, Y: 2},
 				},
 			},
-		},
+		})
-	}
-
 	maps.TestMap(testMap.ID(), testMap, func() {
-		boardState, err := maps.UpdateBoard(testMap.ID(), previousBoardState, rules.Settings{})
+		boardState, err := maps.PostUpdateBoard(testMap, previousBoardState, rules.Settings{})
 
 		require.NoError(t, err)
 

maps/registry_test.go

@@ -10,14 +10,12 @@ import (
 
 const maxBoardWidth, maxBoardHeight = 25, 25
 
-var testSettings rules.Settings = rules.Settings{
+var testSettings rules.Settings = rules.NewSettings(map[string]string{
-	FoodSpawnChance:     25,
+	rules.ParamFoodSpawnChance:     "25",
-	MinimumFood:         1,
+	rules.ParamMinimumFood:         "1",
-	HazardDamagePerTurn: 14,
+	rules.ParamHazardDamagePerTurn: "14",
-	RoyaleSettings: rules.RoyaleSettings{
+	rules.ParamShrinkEveryNTurns:   "1",
-		ShrinkEveryNTurns: 1,
+})
-	},
-}
 
 func TestRegisteredMaps(t *testing.T) {
 	for mapName, gameMap := range globalRegistry {
@@ -96,7 +94,7 @@ func TestRegisteredMaps(t *testing.T) {
 
 			passedBoardState := previousBoardState.Clone()
 			tempBoardState := previousBoardState.Clone()
-			err := gameMap.UpdateBoard(passedBoardState, testSettings, NewBoardStateEditor(tempBoardState))
+			err := gameMap.PostUpdateBoard(passedBoardState, testSettings, NewBoardStateEditor(tempBoardState))
 			require.NoError(t, err, "GameMap.UpdateBoard returned an error")
 			require.Equal(t, previousBoardState, passedBoardState, "BoardState should not be modified directly by GameMap.UpdateBoard")
 		})

maps/rivers_and_bridges.go

@@ -71,7 +71,11 @@ func (m RiverAndBridgesMediumHazardsMap) SetupBoard(initialBoardState *rules.Boa
 	return setupRiverAndBridgesBoard(riversAndBridgesMediumStartPositions, riversAndBridgesMediumHazards, initialBoardState, settings, editor)
 }
 
-func (m RiverAndBridgesMediumHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m RiverAndBridgesMediumHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m RiverAndBridgesMediumHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	return placeRiverAndBridgesFood(lastBoardState, settings, editor)
 }
 
@@ -142,7 +146,11 @@ func (m RiverAndBridgesLargeHazardsMap) SetupBoard(initialBoardState *rules.Boar
 	return setupRiverAndBridgesBoard(riversAndBridgesLargeStartPositions, riversAndBridgesLargeHazards, initialBoardState, settings, editor)
 }
 
-func (m RiverAndBridgesLargeHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m RiverAndBridgesLargeHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m RiverAndBridgesLargeHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	return placeRiverAndBridgesFood(lastBoardState, settings, editor)
 }
 
@@ -241,7 +249,11 @@ func (m RiverAndBridgesExtraLargeHazardsMap) SetupBoard(initialBoardState *rules
 	return setupRiverAndBridgesBoard(riversAndBridgesExtraLargeStartPositions, riversAndBridgesExtraLargeHazards, initialBoardState, settings, editor)
 }
 
-func (m RiverAndBridgesExtraLargeHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m RiverAndBridgesExtraLargeHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m RiverAndBridgesExtraLargeHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	return placeRiverAndBridgesFood(lastBoardState, settings, editor)
 }
 
@@ -355,7 +367,11 @@ func (m IslandsAndBridgesMediumHazardsMap) SetupBoard(initialBoardState *rules.B
 	return setupRiverAndBridgesBoard(islandsAndBridgesMediumStartPositions, islandsAndBridgesMediumHazards, initialBoardState, settings, editor)
 }
 
-func (m IslandsAndBridgesMediumHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m IslandsAndBridgesMediumHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m IslandsAndBridgesMediumHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	return placeRiverAndBridgesFood(lastBoardState, settings, editor)
 }
 
@@ -441,7 +457,11 @@ func (m IslandsAndBridgesLargeHazardsMap) SetupBoard(initialBoardState *rules.Bo
 	return setupRiverAndBridgesBoard(islandsAndBridgesLargeStartPositions, islandsAndBridgesLargeHazards, initialBoardState, settings, editor)
 }
 
-func (m IslandsAndBridgesLargeHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m IslandsAndBridgesLargeHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m IslandsAndBridgesLargeHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	return placeRiverAndBridgesFood(lastBoardState, settings, editor)
 }
 

maps/royale.go

@@ -33,20 +33,25 @@ func (m RoyaleHazardsMap) SetupBoard(lastBoardState *rules.BoardState, settings
 	return StandardMap{}.SetupBoard(lastBoardState, settings, editor)
 }
 
-func (m RoyaleHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m RoyaleHazardsMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m RoyaleHazardsMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	// Use StandardMap to populate food
-	if err := (StandardMap{}).UpdateBoard(lastBoardState, settings, editor); err != nil {
+	if err := (StandardMap{}).PostUpdateBoard(lastBoardState, settings, editor); err != nil {
 		return err
 	}
 
 	// Royale uses the current turn to generate hazards, not the previous turn that's in the board state
 	turn := lastBoardState.Turn + 1
 
-	if settings.RoyaleSettings.ShrinkEveryNTurns < 1 {
+	shrinkEveryNTurns := settings.Int(rules.ParamShrinkEveryNTurns, 0)
+	if shrinkEveryNTurns < 1 {
 		return errors.New("royale game can't shrink more frequently than every turn")
 	}
 
-	if turn < settings.RoyaleSettings.ShrinkEveryNTurns {
+	if turn < shrinkEveryNTurns {
 		return nil
 	}
 
@@ -56,7 +61,7 @@ func (m RoyaleHazardsMap) UpdateBoard(lastBoardState *rules.BoardState, settings
 	// Get random generator for turn zero, because we're regenerating all hazards every time.
 	randGenerator := settings.GetRand(0)
 
-	numShrinks := turn / settings.RoyaleSettings.ShrinkEveryNTurns
+	numShrinks := turn / shrinkEveryNTurns
 	minX, maxX := 0, lastBoardState.Width-1
 	minY, maxY := 0, lastBoardState.Height-1
 	for i := 0; i < numShrinks; i++ {

maps/sinkholes.go

@@ -33,8 +33,12 @@ func (m SinkholesMap) SetupBoard(initialBoardState *rules.BoardState, settings r
 	return (StandardMap{}).SetupBoard(initialBoardState, settings, editor)
 }
 
-func (m SinkholesMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m SinkholesMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-	err := StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+	return nil
+}
+
+func (m SinkholesMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	err := StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 	if err != nil {
 		return err
 	}
@@ -42,8 +46,9 @@ func (m SinkholesMap) UpdateBoard(lastBoardState *rules.BoardState, settings rul
 	currentTurn := lastBoardState.Turn
 	startTurn := 1
 	spawnEveryNTurns := 10
-	if settings.RoyaleSettings.ShrinkEveryNTurns > 0 {
+	shrinkEveryNTurns := settings.Int(rules.ParamShrinkEveryNTurns, 0)
-		spawnEveryNTurns = settings.RoyaleSettings.ShrinkEveryNTurns
+	if shrinkEveryNTurns > 0 {
+		spawnEveryNTurns = shrinkEveryNTurns
 	}
 	maxRings := 5
 	if lastBoardState.Width == 7 {

maps/sinkholes_test.go

@@ -38,7 +38,7 @@ func TestSinkholesMap(t *testing.T) {
 			totalTurns := 100
 			for i := 0; i < totalTurns; i++ {
 				state.Turn = i
-				err = m.UpdateBoard(state, settings, editor)
+				err = m.PostUpdateBoard(state, settings, editor)
 				require.NoError(t, err)
 			}
 			require.NotEmpty(t, state.Hazards)

maps/snail_mode.go

@@ -4,20 +4,22 @@ import (
 	"github.com/BattlesnakeOfficial/rules"
 )
 
-type SnailModeMap struct{}
+type SnailModeMap struct {
+	lastTailPositions map[rules.Point]int // local state is preserved during the turn
+}
 
 // init registers this map in the global registry.
 func init() {
-	globalRegistry.RegisterMap("snail_mode", SnailModeMap{})
+	globalRegistry.RegisterMap("snail_mode", &SnailModeMap{lastTailPositions: nil})
 }
 
 // ID returns a unique identifier for this map.
-func (m SnailModeMap) ID() string {
+func (m *SnailModeMap) ID() string {
 	return "snail_mode"
 }
 
 // Meta returns the non-functional metadata about this map.
-func (m SnailModeMap) Meta() Metadata {
+func (m *SnailModeMap) Meta() Metadata {
 	return Metadata{
 		Name:        "Snail Mode",
 		Description: "Snakes leave behind a trail of hazards",
@@ -31,7 +33,7 @@ func (m SnailModeMap) Meta() Metadata {
 }
 
 // SetupBoard here is pretty 'standard' and doesn't do any special setup for this game mode
-func (m SnailModeMap) SetupBoard(initialBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m *SnailModeMap) SetupBoard(initialBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	rand := settings.GetRand(0)
 
 	if len(initialBoardState.Snakes) > int(m.Meta().MaxPlayers) {
@@ -57,23 +59,6 @@ func (m SnailModeMap) SetupBoard(initialBoardState *rules.BoardState, settings r
 	return nil
 }
 
-// storeTailLocation returns an offboard point that corresponds to the given point.
-// This is useful for storing state that can be accessed next turn.
-func storeTailLocation(point rules.Point, height int) rules.Point {
-	return rules.Point{X: point.X, Y: point.Y + height}
-}
-
-// getPrevTailLocation returns the onboard point that corresponds to an offboard point.
-// This is useful for restoring state that was stored last turn.
-func getPrevTailLocation(point rules.Point, height int) rules.Point {
-	return rules.Point{X: point.X, Y: point.Y - height}
-}
-
-// outOfBounds determines if the given point is out of bounds for the current board size
-func outOfBounds(p rules.Point, w, h int) bool {
-	return p.X < 0 || p.Y < 0 || p.X >= w || p.Y >= h
-}
-
 // doubleTail determine if the snake has a double stacked tail currently
 func doubleTail(snake *rules.Snake) bool {
 	almostTail := snake.Body[len(snake.Body)-2]
@@ -86,12 +71,28 @@ func isEliminated(s *rules.Snake) bool {
 	return s.EliminatedCause != rules.NotEliminated
 }
 
-// UpdateBoard does the work of placing the hazards along the 'snail tail' of snakes
+// PreUpdateBoard stores the tail position of each snake in memory, to be
-// This is responsible for saving the current tail location off the board
+// able to place hazards there after the snakes move.
-// and restoring the previous tail position. This also handles removing one hazards from
+func (m *SnailModeMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
-// the current stacks so the hazards tails fade as the snake moves away.
+	m.lastTailPositions = make(map[rules.Point]int)
-func (m SnailModeMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	for _, snake := range lastBoardState.Snakes {
-	err := StandardMap{}.UpdateBoard(lastBoardState, settings, editor)
+		if isEliminated(&snake) {
+			continue
+		}
+		// Double tail means that the tail will stay on the same square for more
+		// than one turn, so we don't want to spawn hazards
+		if doubleTail(&snake) {
+			continue
+		}
+		m.lastTailPositions[snake.Body[len(snake.Body)-1]] = len(snake.Body)
+	}
+	return nil
+}
+
+// PostUpdateBoard does the work of placing the hazards along the 'snail tail' of snakes
+// This also handles removing one hazards from the current stacks so the hazards tails fade as the snake moves away.
+func (m *SnailModeMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	err := StandardMap{}.PostUpdateBoard(lastBoardState, settings, editor)
 	if err != nil {
 		return err
 	}
@@ -100,79 +101,38 @@ func (m SnailModeMap) UpdateBoard(lastBoardState *rules.BoardState, settings rul
 	// need to be cleared first.
 	editor.ClearHazards()
 
-	// This is a list of all the hazards we want to add for the previous tails
-	// These were stored off board in the previous turn as a way to save state
-	// When we add the locations to this list we have already converted the off-board
-	// points to on-board points
-	tailLocations := make([]rules.Point, 0, len(lastBoardState.Snakes))
-
 	// Count the number of hazards for a given position
-	// Add non-double tail locations to a slice
 	hazardCounts := map[rules.Point]int{}
 	for _, hazard := range lastBoardState.Hazards {
-
-		// discard out of bound
-		if outOfBounds(hazard, lastBoardState.Width, lastBoardState.Height) {
-			onBoardTail := getPrevTailLocation(hazard, lastBoardState.Height)
-			tailLocations = append(tailLocations, onBoardTail)
-		} else {
 		hazardCounts[hazard]++
 	}
-	}
 
 	// Add back existing hazards, but with a stack of 1 less than before.
 	// This has the effect of making the snail-trail disappear over time.
 	for hazard, count := range hazardCounts {
-
 		for i := 0; i < count-1; i++ {
 			editor.AddHazard(hazard)
 		}
 	}
 
-	// Store a stack of hazards for the tail of each snake.  This is stored out
+	// Place a new stack of hazards where each snake's tail used to be
-	// of bounds and then applied on the next turn.  The stack count is equal
+NewHazardLoop:
-	// the lenght of the snake.
+	for location, count := range m.lastTailPositions {
-	for _, snake := range lastBoardState.Snakes {
-		if isEliminated(&snake) {
-			continue
-		}
-
-		// Double tail means that the tail will stay on the same square for more
-		// than one turn, so we don't want to spawn hazards
-		if doubleTail(&snake) {
-			continue
-		}
-
-		tail := snake.Body[len(snake.Body)-1]
-		offBoardTail := storeTailLocation(tail, lastBoardState.Height)
-		for i := 0; i < len(snake.Body); i++ {
-			editor.AddHazard(offBoardTail)
-		}
-	}
-
-	// Read offboard tails and move them to the board. The offboard tails are
-	// stacked based on the length of the snake
-	for _, p := range tailLocations {
-
-		// Skip position if a snakes head occupies it.
-		// Otherwise hazard shows up in the viewer on top of a snake head, but
-		// does not damage the snake, which is visually confusing.
-		isHead := false
 		for _, snake := range lastBoardState.Snakes {
 			if isEliminated(&snake) {
 				continue
 			}
 			head := snake.Body[0]
-			if p.X == head.X && p.Y == head.Y {
+			if location.X == head.X && location.Y == head.Y {
-				isHead = true
+				// Skip position if a snakes head occupies it.
-				break
+				// Otherwise hazard shows up in the viewer on top of a snake head, but
+				// does not damage the snake, which is visually confusing.
+				continue NewHazardLoop
 			}
 		}
-		if isHead {
+		for i := 0; i < count; i++ {
-			continue
+			editor.AddHazard(location)
 		}
-
-		editor.AddHazard(p)
 	}
 
 	return nil

maps/solo_maze.go

@@ -176,7 +176,11 @@ func (m SoloMazeMap) PlaceFood(boardState *rules.BoardState, settings rules.Sett
 	}
 }
 
-func (m SoloMazeMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m SoloMazeMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m SoloMazeMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	currentLevel, e := m.ReadBitState(lastBoardState)
 	if e != nil {
 		return e

maps/standard.go

@@ -57,7 +57,11 @@ func (m StandardMap) SetupBoard(initialBoardState *rules.BoardState, settings ru
 	return nil
 }
 
-func (m StandardMap) UpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+func (m StandardMap) PreUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
+	return nil
+}
+
+func (m StandardMap) PostUpdateBoard(lastBoardState *rules.BoardState, settings rules.Settings, editor Editor) error {
 	rand := settings.GetRand(lastBoardState.Turn)
 
 	foodNeeded := checkFoodNeedingPlacement(rand, settings, lastBoardState)
@@ -69,8 +73,8 @@ func (m StandardMap) UpdateBoard(lastBoardState *rules.BoardState, settings rule
 }
 
 func checkFoodNeedingPlacement(rand rules.Rand, settings rules.Settings, state *rules.BoardState) int {
-	minFood := int(settings.MinimumFood)
+	minFood := settings.Int(rules.ParamMinimumFood, 0)
-	foodSpawnChance := int(settings.FoodSpawnChance)
+	foodSpawnChance := settings.Int(rules.ParamFoodSpawnChance, 0)
 	numCurrentFood := len(state.Food)
 
 	if numCurrentFood < minFood {

maps/standard_test.go

@@ -29,65 +29,29 @@ func TestStandardMapSetupBoard(t *testing.T) {
 			"empty 7x7",
 			rules.NewBoardState(7, 7),
 			rules.MinRand,
-			&rules.BoardState{
+			rules.NewBoardState(7, 7).WithFood([]rules.Point{{X: 3, Y: 3}}),
-				Width:   7,
-				Height:  7,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{{X: 3, Y: 3}},
-				Hazards: []rules.Point{},
-			},
 			nil,
 		},
 		{
 			"not enough room for snakes 7x7",
-			&rules.BoardState{
+			rules.NewBoardState(7, 7).WithSnakes(generateSnakes(17)),
-				Width:   7,
-				Height:  7,
-				Snakes:  generateSnakes(17),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			rules.MinRand,
 			nil,
 			rules.ErrorTooManySnakes,
 		},
 		{
 			"not enough room for snakes 5x5",
-			&rules.BoardState{
+			rules.NewBoardState(5, 5).WithSnakes(generateSnakes(14)),
-				Width:   5,
-				Height:  5,
-				Snakes:  generateSnakes(14),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			rules.MinRand,
 			nil,
 			rules.ErrorTooManySnakes,
 		},
 		{
 			"full 11x11 min",
-			&rules.BoardState{
+			rules.NewBoardState(11, 11).WithSnakes(generateSnakes(8)),
-				Width:   11,
-				Height:  11,
-				Snakes:  generateSnakes(8),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			rules.MinRand,
-			&rules.BoardState{
+			rules.NewBoardState(11, 11).
-				Width:  11,
+				WithFood([]rules.Point{
-				Height: 11,
-				Snakes: []rules.Snake{
-					{ID: "1", Body: []rules.Point{{X: 1, Y: 1}, {X: 1, Y: 1}, {X: 1, Y: 1}}, Health: 100},
-					{ID: "2", Body: []rules.Point{{X: 1, Y: 9}, {X: 1, Y: 9}, {X: 1, Y: 9}}, Health: 100},
-					{ID: "3", Body: []rules.Point{{X: 9, Y: 1}, {X: 9, Y: 1}, {X: 9, Y: 1}}, Health: 100},
-					{ID: "4", Body: []rules.Point{{X: 9, Y: 9}, {X: 9, Y: 9}, {X: 9, Y: 9}}, Health: 100},
-					{ID: "5", Body: []rules.Point{{X: 1, Y: 5}, {X: 1, Y: 5}, {X: 1, Y: 5}}, Health: 100},
-					{ID: "6", Body: []rules.Point{{X: 5, Y: 1}, {X: 5, Y: 1}, {X: 5, Y: 1}}, Health: 100},
-					{ID: "7", Body: []rules.Point{{X: 5, Y: 9}, {X: 5, Y: 9}, {X: 5, Y: 9}}, Health: 100},
-					{ID: "8", Body: []rules.Point{{X: 9, Y: 5}, {X: 9, Y: 5}, {X: 9, Y: 5}}, Health: 100},
-				},
-				Food: []rules.Point{
 					{X: 0, Y: 2},
 					{X: 0, Y: 8},
 					{X: 8, Y: 0},
@@ -97,35 +61,25 @@ func TestStandardMapSetupBoard(t *testing.T) {
 					{X: 4, Y: 10},
 					{X: 10, Y: 4},
 					{X: 5, Y: 5},
-				},
+				}).
-				Hazards: []rules.Point{},
+				WithSnakes([]rules.Snake{
-			},
+					{ID: "1", Body: []rules.Point{{X: 1, Y: 1}, {X: 1, Y: 1}, {X: 1, Y: 1}}, Health: 100},
+					{ID: "2", Body: []rules.Point{{X: 1, Y: 9}, {X: 1, Y: 9}, {X: 1, Y: 9}}, Health: 100},
+					{ID: "3", Body: []rules.Point{{X: 9, Y: 1}, {X: 9, Y: 1}, {X: 9, Y: 1}}, Health: 100},
+					{ID: "4", Body: []rules.Point{{X: 9, Y: 9}, {X: 9, Y: 9}, {X: 9, Y: 9}}, Health: 100},
+					{ID: "5", Body: []rules.Point{{X: 1, Y: 5}, {X: 1, Y: 5}, {X: 1, Y: 5}}, Health: 100},
+					{ID: "6", Body: []rules.Point{{X: 5, Y: 1}, {X: 5, Y: 1}, {X: 5, Y: 1}}, Health: 100},
+					{ID: "7", Body: []rules.Point{{X: 5, Y: 9}, {X: 5, Y: 9}, {X: 5, Y: 9}}, Health: 100},
+					{ID: "8", Body: []rules.Point{{X: 9, Y: 5}, {X: 9, Y: 5}, {X: 9, Y: 5}}, Health: 100},
+				}),
 			nil,
 		},
 		{
 			"full 11x11 max",
-			&rules.BoardState{
+			rules.NewBoardState(11, 11).WithSnakes(generateSnakes(8)),
-				Width:   11,
-				Height:  11,
-				Snakes:  generateSnakes(8),
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 			rules.MaxRand,
-			&rules.BoardState{
+			rules.NewBoardState(11, 11).
-				Width:  11,
+				WithFood([]rules.Point{
-				Height: 11,
-				Snakes: []rules.Snake{
-					{ID: "1", Body: []rules.Point{{X: 5, Y: 1}, {X: 5, Y: 1}, {X: 5, Y: 1}}, Health: 100},
-					{ID: "2", Body: []rules.Point{{X: 5, Y: 9}, {X: 5, Y: 9}, {X: 5, Y: 9}}, Health: 100},
-					{ID: "3", Body: []rules.Point{{X: 9, Y: 5}, {X: 9, Y: 5}, {X: 9, Y: 5}}, Health: 100},
-					{ID: "4", Body: []rules.Point{{X: 1, Y: 5}, {X: 1, Y: 5}, {X: 1, Y: 5}}, Health: 100},
-					{ID: "5", Body: []rules.Point{{X: 1, Y: 9}, {X: 1, Y: 9}, {X: 1, Y: 9}}, Health: 100},
-					{ID: "6", Body: []rules.Point{{X: 9, Y: 1}, {X: 9, Y: 1}, {X: 9, Y: 1}}, Health: 100},
-					{ID: "7", Body: []rules.Point{{X: 9, Y: 9}, {X: 9, Y: 9}, {X: 9, Y: 9}}, Health: 100},
-					{ID: "8", Body: []rules.Point{{X: 1, Y: 1}, {X: 1, Y: 1}, {X: 1, Y: 1}}, Health: 100},
-				},
-				Food: []rules.Point{
 					{X: 6, Y: 0},
 					{X: 6, Y: 10},
 					{X: 10, Y: 6},
@@ -135,9 +89,17 @@ func TestStandardMapSetupBoard(t *testing.T) {
 					{X: 10, Y: 8},
 					{X: 2, Y: 0},
 					{X: 5, Y: 5},
-				},
+				}).
-				Hazards: []rules.Point{},
+				WithSnakes([]rules.Snake{
-			},
+					{ID: "1", Body: []rules.Point{{X: 5, Y: 1}, {X: 5, Y: 1}, {X: 5, Y: 1}}, Health: 100},
+					{ID: "2", Body: []rules.Point{{X: 5, Y: 9}, {X: 5, Y: 9}, {X: 5, Y: 9}}, Health: 100},
+					{ID: "3", Body: []rules.Point{{X: 9, Y: 5}, {X: 9, Y: 5}, {X: 9, Y: 5}}, Health: 100},
+					{ID: "4", Body: []rules.Point{{X: 1, Y: 5}, {X: 1, Y: 5}, {X: 1, Y: 5}}, Health: 100},
+					{ID: "5", Body: []rules.Point{{X: 1, Y: 9}, {X: 1, Y: 9}, {X: 1, Y: 9}}, Health: 100},
+					{ID: "6", Body: []rules.Point{{X: 9, Y: 1}, {X: 9, Y: 1}, {X: 9, Y: 1}}, Health: 100},
+					{ID: "7", Body: []rules.Point{{X: 9, Y: 9}, {X: 9, Y: 9}, {X: 9, Y: 9}}, Health: 100},
+					{ID: "8", Body: []rules.Point{{X: 1, Y: 1}, {X: 1, Y: 1}, {X: 1, Y: 1}}, Health: 100},
+				}),
 			nil,
 		},
 	}
@@ -172,132 +134,51 @@ func TestStandardMapUpdateBoard(t *testing.T) {
 		{
 			"empty no food",
 			rules.NewBoardState(2, 2),
-			rules.Settings{
+			rules.NewSettingsWithParams(rules.ParamFoodSpawnChance, "0", rules.ParamMinimumFood, "0"),
-				FoodSpawnChance: 0,
-				MinimumFood:     0,
-			},
 			rules.MinRand,
-			&rules.BoardState{
+			rules.NewBoardState(2, 2),
-				Width:   2,
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 		},
 		{
 			"empty MinimumFood",
 			rules.NewBoardState(2, 2),
-			rules.Settings{
+			rules.NewSettingsWithParams(rules.ParamFoodSpawnChance, "0", rules.ParamMinimumFood, "2"),
-				FoodSpawnChance: 0,
-				MinimumFood:     2,
-			},
 			rules.MinRand,
-			&rules.BoardState{
+			rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 0}, {X: 0, Y: 1}}),
-				Width:   2,
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{{X: 0, Y: 0}, {X: 0, Y: 1}},
-				Hazards: []rules.Point{},
-			},
 		},
 		{
 			"not empty MinimumFood",
-			&rules.BoardState{
+			rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 1}}),
-				Width:   2,
+			rules.NewSettingsWithParams(rules.ParamFoodSpawnChance, "0", rules.ParamMinimumFood, "2"),
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{{X: 0, Y: 1}},
-				Hazards: []rules.Point{},
-			},
-			rules.Settings{
-				FoodSpawnChance: 0,
-				MinimumFood:     2,
-			},
 			rules.MinRand,
-			&rules.BoardState{
+			rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 1}, {X: 0, Y: 0}}),
-				Width:   2,
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{{X: 0, Y: 1}, {X: 0, Y: 0}},
-				Hazards: []rules.Point{},
-			},
 		},
 		{
 			"empty FoodSpawnChance inactive",
 			rules.NewBoardState(2, 2),
-			rules.Settings{
+			rules.NewSettingsWithParams(rules.ParamFoodSpawnChance, "50", rules.ParamMinimumFood, "0"),
-				FoodSpawnChance: 50,
-				MinimumFood:     0,
-			},
 			rules.MinRand,
-			&rules.BoardState{
+			rules.NewBoardState(2, 2),
-				Width:   2,
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{},
-				Hazards: []rules.Point{},
-			},
 		},
 		{
 			"empty FoodSpawnChance active",
 			rules.NewBoardState(2, 2),
-			rules.Settings{
+			rules.NewSettingsWithParams(rules.ParamFoodSpawnChance, "50", rules.ParamMinimumFood, "0"),
-				FoodSpawnChance: 50,
-				MinimumFood:     0,
-			},
 			rules.MaxRand,
-			&rules.BoardState{
+			rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 1}}),
-				Width:   2,
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{{X: 0, Y: 1}},
-				Hazards: []rules.Point{},
-			},
 		},
 		{
 			"not empty FoodSpawnChance active",
-			&rules.BoardState{
+			rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 0}}),
-				Width:   2,
+			rules.NewSettingsWithParams(rules.ParamFoodSpawnChance, "50", rules.ParamMinimumFood, "0"),
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{{X: 0, Y: 0}},
-				Hazards: []rules.Point{},
-			},
-			rules.Settings{
-				FoodSpawnChance: 50,
-				MinimumFood:     0,
-			},
 			rules.MaxRand,
-			&rules.BoardState{
+			rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 0}, {X: 1, Y: 0}}),
-				Width:   2,
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{{X: 0, Y: 0}, {X: 1, Y: 0}},
-				Hazards: []rules.Point{},
-			},
 		},
 		{
 			"not empty FoodSpawnChance no room",
-			&rules.BoardState{
+			rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 1, Y: 0}, {X: 1, Y: 1}}),
-				Width:   2,
+			rules.NewSettingsWithParams(rules.ParamFoodSpawnChance, "50", rules.ParamMinimumFood, "0"),
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 1, Y: 0}, {X: 1, Y: 1}},
-				Hazards: []rules.Point{},
-			},
-			rules.Settings{
-				FoodSpawnChance: 50,
-				MinimumFood:     0,
-			},
 			rules.MaxRand,
-			&rules.BoardState{
+			rules.NewBoardState(2, 2).WithFood([]rules.Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 1, Y: 0}, {X: 1, Y: 1}}),
-				Width:   2,
-				Height:  2,
-				Snakes:  []rules.Snake{},
-				Food:    []rules.Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 1, Y: 0}, {X: 1, Y: 1}},
-				Hazards: []rules.Point{},
-			},
 		},
 	}
 	for _, test := range tests {
@@ -306,7 +187,7 @@ func TestStandardMapUpdateBoard(t *testing.T) {
 			settings := test.settings.WithRand(test.rand)
 			editor := maps.NewBoardStateEditor(nextBoardState)
 
-			err := m.UpdateBoard(test.initialBoardState.Clone(), settings, editor)
+			err := m.PostUpdateBoard(test.initialBoardState.Clone(), settings, editor)
 
 			require.NoError(t, err)
 			require.Equal(t, test.expected, nextBoardState)

pipeline.go

@@ -38,6 +38,33 @@ var globalRegistry = StageRegistry{
 	StageMovementWrapBoundaries: MoveSnakesWrapped,
 }
 
+// Pipeline is an ordered sequences of game stages which are executed to produce the
+// next game state.
+//
+// If a stage produces an error or an ended game state, the pipeline is halted at that stage.
+type Pipeline interface {
+	// Execute runs the pipeline stages and produces a next game state.
+	//
+	// If any stage produces an error or an ended game state, the pipeline
+	// immediately stops at that stage.
+	//
+	// Errors should be checked and the other results ignored if error is non-nil.
+	//
+	// If the pipeline is already in an error state (this can be checked by calling Err()),
+	// this error will be immediately returned and the pipeline will not run.
+	//
+	// After the pipeline runs, the results will be the result of the last stage that was executed.
+	Execute(*BoardState, Settings, []SnakeMove) (bool, *BoardState, error)
+
+	// Err provides a way to check for errors before/without calling Execute.
+	// Err returns an error if the Pipeline is in an error state.
+	// If this error is not nil, this error will also be returned from Execute, so it is
+	// optional to call Err.
+	// The idea is to reduce error-checking verbosity for the majority of cases where a
+	// Pipeline is immediately executed after construction (i.e. NewPipeline(...).Execute(...)).
+	Err() error
+}
+
 // StageFunc represents a single stage of an ordered pipeline and applies custom logic to the board state each turn.
 // It is expected to modify the boardState directly.
 // The return values are a boolean (to indicate whether the game has ended as a result of the stage)
@@ -46,6 +73,14 @@ var globalRegistry = StageRegistry{
 // Errors should be treated as meaning the stage failed and the board state is now invalid.
 type StageFunc func(*BoardState, Settings, []SnakeMove) (bool, error)
 
+// IsInitialization checks whether the current state means the game is initialising (turn zero).
+// Useful for StageFuncs that need to apply different behaviour on initialisation.
+func IsInitialization(b *BoardState, settings Settings, moves []SnakeMove) bool {
+	// We can safely assume that the game state is in the initialisation phase when
+	// the turn hasn't advanced and the moves are empty
+	return b.Turn <= 0 && len(moves) == 0
+}
+
 // StageRegistry is a mapping of stage names to stage functions
 type StageRegistry map[string]StageFunc
 
@@ -76,32 +111,6 @@ func RegisterPipelineStage(s string, fn StageFunc) {
 	}
 }
 
-// Pipeline is an ordered sequences of game stages which are executed to produce the
-// next game state.
-//
-// If a stage produces an error or an ended game state, the pipeline is halted at that stage.
-type Pipeline interface {
-	// Execute runs the pipeline stages and produces a next game state.
-	//
-	// If any stage produces an error or an ended game state, the pipeline
-	// immediately stops at that stage.
-	//
-	// Errors should be checked and the other results ignored if error is non-nil.
-	//
-	// If the pipeline is already in an error state (this can be checked by calling Err()),
-	// this error will be immediately returned and the pipeline will not run.
-	//
-	// After the pipeline runs, the results will be the result of the last stage that was executed.
-	Execute(*BoardState, Settings, []SnakeMove) (bool, *BoardState, error)
-	// Err provides a way to check for errors before/without calling Execute.
-	// Err returns an error if the Pipeline is in an error state.
-	// If this error is not nil, this error will also be returned from Execute, so it is
-	// optional to call Err.
-	// The idea is to reduce error-checking verbosity for the majority of cases where a
-	// Pipeline is immediately executed after construction (i.e. NewPipeline(...).Execute(...)).
-	Err() error
-}
-
 // pipeline is an implementation of Pipeline
 type pipeline struct {
 	// stages is a list of stages that should be executed from slice start to end

pipeline_internal_test.go

@@ -27,7 +27,7 @@ func TestPipelineRuleset(t *testing.T) {
 		name:     "test",
 		pipeline: p,
 	}
-	ended, err := pr.IsGameOver(&BoardState{})
+	ended, _, err := pr.Execute(&BoardState{}, nil)
 	require.NoError(t, err)
 	require.True(t, ended)
 
@@ -37,7 +37,7 @@ func TestPipelineRuleset(t *testing.T) {
 		name:     "test",
 		pipeline: p,
 	}
-	ended, err = pr.IsGameOver(&BoardState{})
+	ended, _, err = pr.Execute(&BoardState{}, nil)
 	require.NoError(t, err)
 	require.False(t, ended)
 
@@ -56,10 +56,10 @@ func TestPipelineRuleset(t *testing.T) {
 		pipeline: p,
 	}
 	require.Empty(t, b.Food)
-	b, err = pr.ModifyInitialBoardState(b)
+	_, b, err = pr.Execute(b, nil)
 	require.NoError(t, err)
 	require.Empty(t, b.Food, "food should not be added on initialisation phase")
-	b, err = pr.CreateNextBoardState(b, mockSnakeMoves())
+	_, b, err = pr.Execute(b, mockSnakeMoves())
 	require.NoError(t, err)
 	require.NotEmpty(t, b.Food, "fodo should be added now")
 }

pipeline_test.go

@@ -21,17 +21,17 @@ func TestPipeline(t *testing.T) {
 	r.RegisterPipelineStage("astage", mockStageFn(false, nil))
 	p = rules.NewPipelineFromRegistry(r)
 	require.Equal(t, rules.ErrorNoStages, p.Err())
-	_, _, err = p.Execute(&rules.BoardState{}, rules.Settings{}, nil)
+	_, _, err = p.Execute(rules.NewBoardState(0, 0), rules.Settings{}, nil)
 	require.Equal(t, rules.ErrorNoStages, err)
 
 	// test that an unregistered stage name errors
 	p = rules.NewPipelineFromRegistry(r, "doesntexist")
-	_, _, err = p.Execute(&rules.BoardState{}, rules.Settings{}, nil)
+	_, _, err = p.Execute(rules.NewBoardState(0, 0), rules.Settings{}, nil)
 	require.Equal(t, rules.ErrorStageNotFound, p.Err())
 	require.Equal(t, rules.ErrorStageNotFound, err)
 
 	// simplest case - one stage
-	ended, next, err := rules.NewPipelineFromRegistry(r, "astage").Execute(&rules.BoardState{}, rules.Settings{}, nil)
+	ended, next, err := rules.NewPipelineFromRegistry(r, "astage").Execute(rules.NewBoardState(0, 0), rules.Settings{}, nil)
 	require.NoError(t, err)
 	require.NoError(t, err)
 	require.NotNil(t, next)
@@ -39,20 +39,20 @@ func TestPipeline(t *testing.T) {
 
 	// test that the pipeline short-circuits for a stage that errors
 	r.RegisterPipelineStage("errors", mockStageFn(false, errors.New("")))
-	ended, next, err = rules.NewPipelineFromRegistry(r, "errors", "astage").Execute(&rules.BoardState{}, rules.Settings{}, nil)
+	ended, next, err = rules.NewPipelineFromRegistry(r, "errors", "astage").Execute(rules.NewBoardState(0, 0), rules.Settings{}, nil)
 	require.Error(t, err)
 	require.NotNil(t, next)
 	require.False(t, ended)
 
 	// test that the pipeline short-circuits for a stage that ends
 	r.RegisterPipelineStage("ends", mockStageFn(true, nil))
-	ended, next, err = rules.NewPipelineFromRegistry(r, "ends", "astage").Execute(&rules.BoardState{}, rules.Settings{}, nil)
+	ended, next, err = rules.NewPipelineFromRegistry(r, "ends", "astage").Execute(rules.NewBoardState(0, 0), rules.Settings{}, nil)
 	require.NoError(t, err)
 	require.NotNil(t, next)
 	require.True(t, ended)
 
 	// test that the pipeline runs normally for multiple stages
-	ended, next, err = rules.NewPipelineFromRegistry(r, "astage", "ends").Execute(&rules.BoardState{}, rules.Settings{}, nil)
+	ended, next, err = rules.NewPipelineFromRegistry(r, "astage", "ends").Execute(rules.NewBoardState(0, 0), rules.Settings{}, nil)
 	require.NoError(t, err)
 	require.NotNil(t, next)
 	require.True(t, ended)

royale.go

@@ -14,26 +14,6 @@ var royaleRulesetStages = []string{
 	StageSpawnHazardsShrinkMap,
 }
 
-type RoyaleRuleset struct {
-	StandardRuleset
-
-	ShrinkEveryNTurns int
-}
-
-func (r *RoyaleRuleset) Name() string { return GameTypeRoyale }
-
-func (r RoyaleRuleset) Execute(bs *BoardState, s Settings, sm []SnakeMove) (bool, *BoardState, error) {
-	return NewPipeline(royaleRulesetStages...).Execute(bs, s, sm)
-}
-
-func (r *RoyaleRuleset) CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
-	if r.StandardRuleset.HazardDamagePerTurn < 1 {
-		return nil, errors.New("royale damage per turn must be greater than zero")
-	}
-	_, nextState, err := r.Execute(prevState, r.Settings(), moves)
-	return nextState, err
-}
-
 func PopulateHazardsRoyale(b *BoardState, settings Settings, moves []SnakeMove) (bool, error) {
 	if IsInitialization(b, settings, moves) {
 		return false, nil
@@ -43,17 +23,18 @@ func PopulateHazardsRoyale(b *BoardState, settings Settings, moves []SnakeMove)
 	// Royale uses the current turn to generate hazards, not the previous turn that's in the board state
 	turn := b.Turn + 1
 
-	if settings.RoyaleSettings.ShrinkEveryNTurns < 1 {
+	shrinkEveryNTurns := settings.Int(ParamShrinkEveryNTurns, 0)
+	if shrinkEveryNTurns < 1 {
 		return false, errors.New("royale game can't shrink more frequently than every turn")
 	}
 
-	if turn < settings.RoyaleSettings.ShrinkEveryNTurns {
+	if turn < shrinkEveryNTurns {
 		return false, nil
 	}
 
 	randGenerator := settings.GetRand(0)
 
-	numShrinks := turn / settings.RoyaleSettings.ShrinkEveryNTurns
+	numShrinks := turn / shrinkEveryNTurns
 	minX, maxX := 0, b.Width-1
 	minY, maxY := 0, b.Height-1
 	for i := 0; i < numShrinks; i++ {
@@ -72,22 +53,10 @@ func PopulateHazardsRoyale(b *BoardState, settings Settings, moves []SnakeMove)
 	for x := 0; x < b.Width; x++ {
 		for y := 0; y < b.Height; y++ {
 			if x < minX || x > maxX || y < minY || y > maxY {
-				b.Hazards = append(b.Hazards, Point{x, y})
+				b.Hazards = append(b.Hazards, Point{X: x, Y: y})
 			}
 		}
 	}
 
 	return false, nil
 }
-
-func (r *RoyaleRuleset) IsGameOver(b *BoardState) (bool, error) {
-	return GameOverStandard(b, r.Settings(), nil)
-}
-
-func (r RoyaleRuleset) Settings() Settings {
-	s := r.StandardRuleset.Settings()
-	s.RoyaleSettings = RoyaleSettings{
-		ShrinkEveryNTurns: r.ShrinkEveryNTurns,
-	}
-	return s
-}

royale_test.go

@@ -2,14 +2,19 @@ package rules
 
 import (
 	"errors"
+	"fmt"
 	"math/rand"
 	"testing"
 
 	"github.com/stretchr/testify/require"
 )
 
-func TestRoyaleRulesetInterface(t *testing.T) {
+func getRoyaleRuleset(hazardDamagePerTurn, shrinkEveryNTurns int) Ruleset {
-	var _ Ruleset = (*RoyaleRuleset)(nil)
+	settings := NewSettingsWithParams(
+		ParamHazardDamagePerTurn, fmt.Sprint(hazardDamagePerTurn),
+		ParamShrinkEveryNTurns, fmt.Sprint(shrinkEveryNTurns),
+	)
+	return NewRulesetBuilder().WithSettings(settings).NamedRuleset(GameTypeRoyale)
 }
 
 func TestRoyaleDefaultSanity(t *testing.T) {
@@ -19,24 +24,19 @@ func TestRoyaleDefaultSanity(t *testing.T) {
 			{ID: "2", Body: []Point{{X: 0, Y: 1}}},
 		},
 	}
-	r := RoyaleRuleset{StandardRuleset: StandardRuleset{HazardDamagePerTurn: 1}, ShrinkEveryNTurns: 0}
+	r := getRoyaleRuleset(1, 0)
-	_, err := r.CreateNextBoardState(boardState, []SnakeMove{{"1", "right"}, {"2", "right"}})
+	_, _, err := r.Execute(boardState, []SnakeMove{{"1", "right"}, {"2", "right"}})
 	require.Error(t, err)
 	require.Equal(t, errors.New("royale game can't shrink more frequently than every turn"), err)
 
-	r = RoyaleRuleset{ShrinkEveryNTurns: 1}
+	r = getRoyaleRuleset(1, 1)
-	_, err = r.CreateNextBoardState(boardState, []SnakeMove{})
+	_, boardState, err = r.Execute(boardState, []SnakeMove{})
-	require.Error(t, err)
-	require.Equal(t, errors.New("royale damage per turn must be greater than zero"), err)
-
-	r = RoyaleRuleset{StandardRuleset: StandardRuleset{HazardDamagePerTurn: 1}, ShrinkEveryNTurns: 1}
-	boardState, err = r.CreateNextBoardState(boardState, []SnakeMove{})
 	require.NoError(t, err)
 	require.Len(t, boardState.Hazards, 0)
 }
 
 func TestRoyaleName(t *testing.T) {
-	r := RoyaleRuleset{}
+	r := getRoyaleRuleset(0, 0)
 	require.Equal(t, "royale", r.Name())
 }
 
@@ -57,39 +57,39 @@ func TestRoyaleHazards(t *testing.T) {
 		{Width: 3, Height: 3, Turn: 9, ShrinkEveryNTurns: 10, ExpectedHazards: []Point{}},
 		{
 			Width: 3, Height: 3, Turn: 10, ShrinkEveryNTurns: 10,
-			ExpectedHazards: []Point{{0, 0}, {0, 1}, {0, 2}},
+			ExpectedHazards: []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 0, Y: 2}},
 		},
 		{
 			Width: 3, Height: 3, Turn: 11, ShrinkEveryNTurns: 10,
-			ExpectedHazards: []Point{{0, 0}, {0, 1}, {0, 2}},
+			ExpectedHazards: []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 0, Y: 2}},
 		},
 		{
 			Width: 3, Height: 3, Turn: 19, ShrinkEveryNTurns: 10,
-			ExpectedHazards: []Point{{0, 0}, {0, 1}, {0, 2}},
+			ExpectedHazards: []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 0, Y: 2}},
 		},
 		{
 			Width: 3, Height: 3, Turn: 20, ShrinkEveryNTurns: 10,
-			ExpectedHazards: []Point{{0, 0}, {0, 1}, {0, 2}, {1, 2}, {2, 2}},
+			ExpectedHazards: []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 0, Y: 2}, {X: 1, Y: 2}, {X: 2, Y: 2}},
 		},
 		{
 			Width: 3, Height: 3, Turn: 31, ShrinkEveryNTurns: 10,
-			ExpectedHazards: []Point{{0, 0}, {0, 1}, {0, 2}, {1, 1}, {1, 2}, {2, 1}, {2, 2}},
+			ExpectedHazards: []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 0, Y: 2}, {X: 1, Y: 1}, {X: 1, Y: 2}, {X: 2, Y: 1}, {X: 2, Y: 2}},
 		},
 		{
 			Width: 3, Height: 3, Turn: 42, ShrinkEveryNTurns: 10,
-			ExpectedHazards: []Point{{0, 0}, {0, 1}, {0, 2}, {1, 0}, {1, 1}, {1, 2}, {2, 0}, {2, 1}, {2, 2}},
+			ExpectedHazards: []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 0, Y: 2}, {X: 1, Y: 0}, {X: 1, Y: 1}, {X: 1, Y: 2}, {X: 2, Y: 0}, {X: 2, Y: 1}, {X: 2, Y: 2}},
 		},
 		{
 			Width: 3, Height: 3, Turn: 53, ShrinkEveryNTurns: 10,
-			ExpectedHazards: []Point{{0, 0}, {0, 1}, {0, 2}, {1, 0}, {1, 1}, {1, 2}, {2, 0}, {2, 1}, {2, 2}},
+			ExpectedHazards: []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 0, Y: 2}, {X: 1, Y: 0}, {X: 1, Y: 1}, {X: 1, Y: 2}, {X: 2, Y: 0}, {X: 2, Y: 1}, {X: 2, Y: 2}},
 		},
 		{
 			Width: 3, Height: 3, Turn: 64, ShrinkEveryNTurns: 10,
-			ExpectedHazards: []Point{{0, 0}, {0, 1}, {0, 2}, {1, 0}, {1, 1}, {1, 2}, {2, 0}, {2, 1}, {2, 2}},
+			ExpectedHazards: []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 0, Y: 2}, {X: 1, Y: 0}, {X: 1, Y: 1}, {X: 1, Y: 2}, {X: 2, Y: 0}, {X: 2, Y: 1}, {X: 2, Y: 2}},
 		},
 		{
 			Width: 3, Height: 3, Turn: 6987, ShrinkEveryNTurns: 10,
-			ExpectedHazards: []Point{{0, 0}, {0, 1}, {0, 2}, {1, 0}, {1, 1}, {1, 2}, {2, 0}, {2, 1}, {2, 2}},
+			ExpectedHazards: []Point{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 0, Y: 2}, {X: 1, Y: 0}, {X: 1, Y: 1}, {X: 1, Y: 2}, {X: 2, Y: 0}, {X: 2, Y: 1}, {X: 2, Y: 2}},
 		},
 	}
 
@@ -99,12 +99,10 @@ func TestRoyaleHazards(t *testing.T) {
 			Width:  test.Width,
 			Height: test.Height,
 		}
-		settings := Settings{
+		settings := NewSettingsWithParams(
-			HazardDamagePerTurn: 1,
+			ParamHazardDamagePerTurn, "1",
-			RoyaleSettings: RoyaleSettings{
+			ParamShrinkEveryNTurns, fmt.Sprint(test.ShrinkEveryNTurns),
-				ShrinkEveryNTurns: test.ShrinkEveryNTurns,
+		).WithSeed(seed)
-			},
-		}.WithSeed(seed)
 
 		_, err := PopulateHazardsRoyale(b, settings, mockSnakeMoves())
 		require.Equal(t, test.Error, err)
@@ -139,12 +137,12 @@ var royaleCaseHazardsPlaced = gameTestCase{
 		Snakes: []Snake{
 			{
 				ID:     "one",
-				Body:   []Point{{1, 1}, {1, 2}},
+				Body:   []Point{{X: 1, Y: 1}, {X: 1, Y: 2}},
 				Health: 100,
 			},
 			{
 				ID:     "two",
-				Body:   []Point{{3, 4}, {3, 3}},
+				Body:   []Point{{X: 3, Y: 4}, {X: 3, Y: 3}},
 				Health: 100,
 			},
 			{
@@ -154,7 +152,7 @@ var royaleCaseHazardsPlaced = gameTestCase{
 				EliminatedCause: EliminatedByOutOfBounds,
 			},
 		},
-		Food:    []Point{{0, 0}, {1, 0}},
+		Food:    []Point{{X: 0, Y: 0}, {X: 1, Y: 0}},
 		Hazards: []Point{},
 	},
 	[]SnakeMove{
@@ -169,12 +167,12 @@ var royaleCaseHazardsPlaced = gameTestCase{
 		Snakes: []Snake{
 			{
 				ID:     "one",
-				Body:   []Point{{1, 0}, {1, 1}, {1, 1}},
+				Body:   []Point{{X: 1, Y: 0}, {X: 1, Y: 1}, {X: 1, Y: 1}},
 				Health: 100,
 			},
 			{
 				ID:     "two",
-				Body:   []Point{{3, 5}, {3, 4}},
+				Body:   []Point{{X: 3, Y: 5}, {X: 3, Y: 4}},
 				Health: 99,
 			},
 			{
@@ -184,7 +182,7 @@ var royaleCaseHazardsPlaced = gameTestCase{
 				EliminatedCause: EliminatedByOutOfBounds,
 			},
 		},
-		Food:    []Point{{0, 0}},
+		Food:    []Point{{X: 0, Y: 0}},
 		Hazards: []Point{{X: 0, Y: 0}, {X: 1, Y: 0}, {X: 2, Y: 0}, {X: 3, Y: 0}, {X: 4, Y: 0}, {X: 5, Y: 0}, {X: 6, Y: 0}, {X: 7, Y: 0}, {X: 8, Y: 0}, {X: 9, Y: 0}},
 	},
 }
@@ -204,22 +202,14 @@ func TestRoyaleCreateNextBoardState(t *testing.T) {
 		*s2,
 		royaleCaseHazardsPlaced,
 	}
-	r := RoyaleRuleset{
-		StandardRuleset: StandardRuleset{
-			HazardDamagePerTurn: 1,
-		},
-		ShrinkEveryNTurns: 1,
-	}
 	rb := NewRulesetBuilder().WithParams(map[string]string{
-		ParamGameType:            GameTypeRoyale,
 		ParamHazardDamagePerTurn: "1",
 		ParamShrinkEveryNTurns:   "1",
 	}).WithSeed(1234)
 	for _, gc := range cases {
 		rand.Seed(1234)
-		gc.requireValidNextState(t, &r)
+		// test a RulesBuilder constructed instance
-		// also test a RulesBuilder constructed instance
+		gc.requireValidNextState(t, rb.NamedRuleset(GameTypeRoyale))
-		gc.requireValidNextState(t, rb.Ruleset())
 		// also test a pipeline with the same settings
 		gc.requireValidNextState(t, rb.PipelineRuleset(GameTypeRoyale, NewPipeline(royaleRulesetStages...)))
 	}

ruleset.go

@@ -1,16 +1,15 @@
 package rules
 
-import (
-	"strconv"
-)
-
 type Ruleset interface {
+	// Returns the name of the ruleset, if applicable.
 	Name() string
-	ModifyInitialBoardState(initialState *BoardState) (*BoardState, error)
+
-	CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error)
+	// Returns the settings used by the ruleset.
-	IsGameOver(state *BoardState) (bool, error)
-	// Settings provides the game settings that are relevant to the ruleset.
 	Settings() Settings
+
+	// Processes the next turn of the ruleset, returning whether the game has ended, the next BoardState, or an error.
+	// For turn zero (initialization), moves will be left empty.
+	Execute(prevState *BoardState, moves []SnakeMove) (gameOver bool, nextState *BoardState, err error)
 }
 
 type SnakeMove struct {
@@ -18,68 +17,12 @@ type SnakeMove struct {
 	Move string
 }
 
-// Settings contains all settings relevant to a game.
-// It is used by game logic to take a previous game state and produce a next game state.
-type Settings struct {
-	FoodSpawnChance     int            `json:"foodSpawnChance"`
-	MinimumFood         int            `json:"minimumFood"`
-	HazardDamagePerTurn int            `json:"hazardDamagePerTurn"`
-	HazardMap           string         `json:"hazardMap"`
-	HazardMapAuthor     string         `json:"hazardMapAuthor"`
-	RoyaleSettings      RoyaleSettings `json:"royale"`
-	SquadSettings       SquadSettings  `json:"squad"` // Deprecated, provided with default fields for API compatibility
-
-	rand Rand
-	seed int64
-}
-
-// Get a random number generator initialized based on the seed and current turn.
-func (settings Settings) GetRand(turn int) Rand {
-	// Allow overriding the random generator for testing
-	if settings.rand != nil {
-		return settings.rand
-	}
-
-	if settings.seed != 0 {
-		return NewSeedRand(settings.seed + int64(turn))
-	}
-
-	// Default to global random number generator if neither seed or rand are set.
-	return GlobalRand
-}
-
-func (settings Settings) WithRand(rand Rand) Settings {
-	settings.rand = rand
-	return settings
-}
-
-func (settings Settings) Seed() int64 {
-	return settings.seed
-}
-
-func (settings Settings) WithSeed(seed int64) Settings {
-	settings.seed = seed
-	return settings
-}
-
-// RoyaleSettings contains settings that are specific to the "royale" game mode
-type RoyaleSettings struct {
-	ShrinkEveryNTurns int `json:"shrinkEveryNTurns"`
-}
-
-// SquadSettings contains settings that are specific to the "squad" game mode
-type SquadSettings struct {
-	AllowBodyCollisions bool `json:"allowBodyCollisions"`
-	SharedElimination   bool `json:"sharedElimination"`
-	SharedHealth        bool `json:"sharedHealth"`
-	SharedLength        bool `json:"sharedLength"`
-}
-
 type rulesetBuilder struct {
 	params   map[string]string // game customisation parameters
 	seed     int64             // used for random events in games
 	rand     Rand              // used for random number generation
 	solo     bool              // if true, only 1 alive snake is required to keep the game from ending
+	settings *Settings         // used to set settings directly instead of via string params
 }
 
 // NewRulesetBuilder returns an instance of a builder for the Ruleset types.
@@ -89,7 +32,7 @@ func NewRulesetBuilder() *rulesetBuilder {
 	}
 }
 
-// WithParams accepts a map of game parameters for customizing games.
+// WithParams accepts a map of string parameters for customizing games.
 //
 // Parameters are copied. If called multiple times, parameters are merged such that:
 //   - existing keys in both maps get overwritten by the new ones
@@ -125,13 +68,14 @@ func (rb *rulesetBuilder) WithSolo(value bool) *rulesetBuilder {
 	return rb
 }
 
-// Ruleset constructs a customised ruleset using the parameters passed to the builder.
+// WithSettings sets the settings object for the ruleset directly.
-func (rb rulesetBuilder) Ruleset() PipelineRuleset {
+func (rb *rulesetBuilder) WithSettings(settings Settings) *rulesetBuilder {
-	name, ok := rb.params[ParamGameType]
+	rb.settings = &settings
-	if !ok {
+	return rb
-		name = GameTypeStandard
+}
-	}
 
+// NamedRuleset constructs a known ruleset by using name to look up a standard pipeline.
+func (rb rulesetBuilder) NamedRuleset(name string) Ruleset {
 	var stages []string
 	if rb.solo {
 		stages = append(stages, StageGameOverSoloSnake)
@@ -153,63 +97,28 @@ func (rb rulesetBuilder) Ruleset() PipelineRuleset {
 	case GameTypeWrapped:
 		stages = append(stages, wrappedRulesetStages[1:]...)
 	default:
+		name = GameTypeStandard
 		stages = append(stages, standardRulesetStages[1:]...)
 	}
 	return rb.PipelineRuleset(name, NewPipeline(stages...))
 }
 
-// PipelineRuleset provides an implementation of the Ruleset using a pipeline with a name.
+// PipelineRuleset constructs a ruleset with the given name and pipeline using the parameters passed to the builder.
-// It is intended to facilitate transitioning away from legacy Ruleset implementations to Pipeline
+// This can be used to create custom rulesets.
-// implementations.
+func (rb rulesetBuilder) PipelineRuleset(name string, p Pipeline) Ruleset {
-func (rb rulesetBuilder) PipelineRuleset(name string, p Pipeline) PipelineRuleset {
+	var settings Settings
+	if rb.settings != nil {
+		settings = *rb.settings
+	} else {
+		settings = NewSettings(rb.params).WithRand(rb.rand).WithSeed(rb.seed)
+	}
 	return &pipelineRuleset{
 		name:     name,
 		pipeline: p,
-		settings: Settings{
+		settings: settings,
-			FoodSpawnChance:     paramsInt(rb.params, ParamFoodSpawnChance, 0),
-			MinimumFood:         paramsInt(rb.params, ParamMinimumFood, 0),
-			HazardDamagePerTurn: paramsInt(rb.params, ParamHazardDamagePerTurn, 0),
-			HazardMap:           rb.params[ParamHazardMap],
-			HazardMapAuthor:     rb.params[ParamHazardMapAuthor],
-			RoyaleSettings: RoyaleSettings{
-				ShrinkEveryNTurns: paramsInt(rb.params, ParamShrinkEveryNTurns, 0),
-			},
-			rand: rb.rand,
-			seed: rb.seed,
-		},
 	}
 }
 
-// paramsBool returns the boolean value for the specified parameter.
-// If the parameter doesn't exist, the default value will be returned.
-// If the parameter does exist, but is not "true", false will be returned.
-func paramsBool(params map[string]string, paramName string, defaultValue bool) bool {
-	if val, ok := params[paramName]; ok {
-		return val == "true"
-	}
-	return defaultValue
-}
-
-// paramsInt returns the int value for the specified parameter.
-// If the parameter doesn't exist, the default value will be returned.
-// If the parameter does exist, but is not a valid int, the default value will be returned.
-func paramsInt(params map[string]string, paramName string, defaultValue int) int {
-	if val, ok := params[paramName]; ok {
-		i, err := strconv.Atoi(val)
-		if err == nil {
-			return i
-		}
-	}
-	return defaultValue
-}
-
-// PipelineRuleset groups the Pipeline and Ruleset methods.
-// It is intended to facilitate a transition from Ruleset legacy code to Pipeline code.
-type PipelineRuleset interface {
-	Ruleset
-	Pipeline
-}
-
 type pipelineRuleset struct {
 	pipeline Pipeline
 	name     string
@@ -225,33 +134,10 @@ func (r pipelineRuleset) Settings() Settings {
 func (r pipelineRuleset) Name() string { return r.name }
 
 // impl Ruleset
-// IMPORTANT: this implementation of IsGameOver deviates from the previous Ruleset implementations
+func (r pipelineRuleset) Execute(bs *BoardState, sm []SnakeMove) (bool, *BoardState, error) {
-// in that it checks if the *NEXT* state results in game over, not the previous state.
+	return r.pipeline.Execute(bs, r.Settings(), sm)
-// This is due to the design of pipelines / stage functions not having a distinction between
-// checking for game over and producing a next state.
-func (r *pipelineRuleset) IsGameOver(b *BoardState) (bool, error) {
-	gameover, _, err := r.Execute(b, r.Settings(), nil) // checks if next state is game over
-	return gameover, err
 }
 
-// impl Ruleset
-func (r pipelineRuleset) ModifyInitialBoardState(initialState *BoardState) (*BoardState, error) {
-	_, nextState, err := r.Execute(initialState, r.Settings(), nil)
-	return nextState, err
-}
-
-// impl Pipeline
-func (r pipelineRuleset) Execute(bs *BoardState, s Settings, sm []SnakeMove) (bool, *BoardState, error) {
-	return r.pipeline.Execute(bs, s, sm)
-}
-
-// impl Ruleset
-func (r pipelineRuleset) CreateNextBoardState(bs *BoardState, sm []SnakeMove) (*BoardState, error) {
-	_, nextState, err := r.Execute(bs, r.Settings(), sm)
-	return nextState, err
-}
-
-// impl Pipeline
 func (r pipelineRuleset) Err() error {
 	return r.pipeline.Err()
 }

ruleset_internal_test.go

@@ -10,31 +10,6 @@ import (
 	_ "github.com/BattlesnakeOfficial/rules/test"
 )
 
-func TestParamInt(t *testing.T) {
-	require.Equal(t, 5, paramsInt(nil, "test", 5), "nil map")
-	require.Equal(t, 10, paramsInt(map[string]string{}, "foo", 10), "empty map")
-	require.Equal(t, 10, paramsInt(map[string]string{"hullo": "there"}, "hullo", 10), "invalid value")
-	require.Equal(t, 20, paramsInt(map[string]string{"bonjour": "20"}, "bonjour", 20), "valid value")
-}
-
-func TestParamBool(t *testing.T) {
-	// missing values default to specified value
-	require.Equal(t, true, paramsBool(nil, "test", true), "nil map true")
-	require.Equal(t, false, paramsBool(nil, "test", false), "nil map false")
-
-	// missing values default to specified value
-	require.Equal(t, true, paramsBool(map[string]string{}, "foo", true), "empty map true")
-	require.Equal(t, false, paramsBool(map[string]string{}, "foo", false), "empty map false")
-
-	// invalid values (exist but not booL) default to false
-	require.Equal(t, false, paramsBool(map[string]string{"hullo": "there"}, "hullo", true), "invalid value default true")
-	require.Equal(t, false, paramsBool(map[string]string{"hullo": "there"}, "hullo", false), "invalid value default false")
-
-	// valid values ignore defaults
-	require.Equal(t, false, paramsBool(map[string]string{"bonjour": "false"}, "bonjour", false), "valid value false")
-	require.Equal(t, true, paramsBool(map[string]string{"bonjour": "true"}, "bonjour", false), "valid value true")
-}
-
 func TestRulesetError(t *testing.T) {
 	err := (error)(RulesetError("test error string"))
 	require.Equal(t, "test error string", err.Error())
@@ -42,10 +17,10 @@ func TestRulesetError(t *testing.T) {
 
 func TestRulesetBuilderInternals(t *testing.T) {
 	// test Royale with seed
-	rsb := NewRulesetBuilder().WithSeed(3).WithParams(map[string]string{ParamGameType: GameTypeRoyale})
+	rsb := NewRulesetBuilder().WithSeed(3)
 	require.Equal(t, int64(3), rsb.seed)
-	require.Equal(t, GameTypeRoyale, rsb.Ruleset().Name())
+	require.Equal(t, GameTypeRoyale, rsb.NamedRuleset(GameTypeRoyale).Name())
-	require.Equal(t, int64(3), rsb.Ruleset().Settings().Seed())
+	require.Equal(t, int64(3), rsb.NamedRuleset(GameTypeRoyale).Settings().Seed())
 
 	// test parameter merging
 	rsb = NewRulesetBuilder().

ruleset_test.go

@@ -5,102 +5,13 @@ import (
 	"testing"
 
 	"github.com/BattlesnakeOfficial/rules"
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-func TestStandardRulesetSettings(t *testing.T) {
-	ruleset := rules.StandardRuleset{
-		MinimumFood:         5,
-		FoodSpawnChance:     10,
-		HazardDamagePerTurn: 10,
-		HazardMap:           "hz_spiral",
-		HazardMapAuthor:     "altersaddle",
-	}
-	assert.Equal(t, ruleset.MinimumFood, ruleset.Settings().MinimumFood)
-	assert.Equal(t, ruleset.FoodSpawnChance, ruleset.Settings().FoodSpawnChance)
-	assert.Equal(t, ruleset.HazardDamagePerTurn, ruleset.Settings().HazardDamagePerTurn)
-	assert.Equal(t, ruleset.HazardMap, ruleset.Settings().HazardMap)
-	assert.Equal(t, ruleset.HazardMapAuthor, ruleset.Settings().HazardMapAuthor)
-}
-
-func TestWrappedRulesetSettings(t *testing.T) {
-	ruleset := rules.WrappedRuleset{
-		StandardRuleset: rules.StandardRuleset{
-			MinimumFood:         5,
-			FoodSpawnChance:     10,
-			HazardDamagePerTurn: 10,
-			HazardMap:           "hz_spiral",
-			HazardMapAuthor:     "altersaddle",
-		},
-	}
-	assert.Equal(t, ruleset.MinimumFood, ruleset.Settings().MinimumFood)
-	assert.Equal(t, ruleset.FoodSpawnChance, ruleset.Settings().FoodSpawnChance)
-	assert.Equal(t, ruleset.HazardDamagePerTurn, ruleset.Settings().HazardDamagePerTurn)
-	assert.Equal(t, ruleset.HazardMap, ruleset.Settings().HazardMap)
-	assert.Equal(t, ruleset.HazardMapAuthor, ruleset.Settings().HazardMapAuthor)
-}
-
-func TestSoloRulesetSettings(t *testing.T) {
-	ruleset := rules.SoloRuleset{
-		StandardRuleset: rules.StandardRuleset{
-			MinimumFood:         5,
-			FoodSpawnChance:     10,
-			HazardDamagePerTurn: 10,
-			HazardMap:           "hz_spiral",
-			HazardMapAuthor:     "altersaddle",
-		},
-	}
-	assert.Equal(t, ruleset.MinimumFood, ruleset.Settings().MinimumFood)
-	assert.Equal(t, ruleset.FoodSpawnChance, ruleset.Settings().FoodSpawnChance)
-	assert.Equal(t, ruleset.HazardDamagePerTurn, ruleset.Settings().HazardDamagePerTurn)
-	assert.Equal(t, ruleset.HazardMap, ruleset.Settings().HazardMap)
-	assert.Equal(t, ruleset.HazardMapAuthor, ruleset.Settings().HazardMapAuthor)
-}
-
-func TestRoyaleRulesetSettings(t *testing.T) {
-	ruleset := rules.RoyaleRuleset{
-		ShrinkEveryNTurns: 12,
-		StandardRuleset: rules.StandardRuleset{
-			MinimumFood:         5,
-			FoodSpawnChance:     10,
-			HazardDamagePerTurn: 10,
-			HazardMap:           "hz_spiral",
-			HazardMapAuthor:     "altersaddle",
-		},
-	}
-	assert.Equal(t, ruleset.ShrinkEveryNTurns, ruleset.Settings().RoyaleSettings.ShrinkEveryNTurns)
-	assert.Equal(t, ruleset.MinimumFood, ruleset.Settings().MinimumFood)
-	assert.Equal(t, ruleset.FoodSpawnChance, ruleset.Settings().FoodSpawnChance)
-	assert.Equal(t, ruleset.HazardDamagePerTurn, ruleset.Settings().HazardDamagePerTurn)
-	assert.Equal(t, ruleset.HazardMap, ruleset.Settings().HazardMap)
-	assert.Equal(t, ruleset.HazardMapAuthor, ruleset.Settings().HazardMapAuthor)
-}
-
-func TestConstrictorRulesetSettings(t *testing.T) {
-	ruleset := rules.ConstrictorRuleset{
-		StandardRuleset: rules.StandardRuleset{
-			MinimumFood:         5,
-			FoodSpawnChance:     10,
-			HazardDamagePerTurn: 10,
-			HazardMap:           "hz_spiral",
-			HazardMapAuthor:     "altersaddle",
-		},
-	}
-	assert.Equal(t, ruleset.MinimumFood, ruleset.Settings().MinimumFood)
-	assert.Equal(t, ruleset.FoodSpawnChance, ruleset.Settings().FoodSpawnChance)
-	assert.Equal(t, ruleset.HazardDamagePerTurn, ruleset.Settings().HazardDamagePerTurn)
-	assert.Equal(t, ruleset.HazardMap, ruleset.Settings().HazardMap)
-	assert.Equal(t, ruleset.HazardMapAuthor, ruleset.Settings().HazardMapAuthor)
-}
-
 func TestRulesetBuilder(t *testing.T) {
 	// Test that a fresh instance can produce a Ruleset
-	require.NotNil(t, rules.NewRulesetBuilder().Ruleset())
+	require.NotNil(t, rules.NewRulesetBuilder().NamedRuleset(""))
-	require.Equal(t, rules.GameTypeStandard, rules.NewRulesetBuilder().Ruleset().Name(), "should default to standard game")
+	require.Equal(t, rules.GameTypeStandard, rules.NewRulesetBuilder().NamedRuleset("").Name(), "should default to standard game")
-
-	// test nil safety / defaults
-	require.NotNil(t, rules.NewRulesetBuilder().Ruleset())
 
 	// make sure it works okay for lots of game types
 	expectedResults := []struct {
@@ -120,32 +31,23 @@ func TestRulesetBuilder(t *testing.T) {
 
 			rsb.WithParams(map[string]string{
 				// apply the standard rule params
-				rules.ParamGameType:            expected.GameType,
 				rules.ParamFoodSpawnChance:     "10",
 				rules.ParamMinimumFood:         "5",
 				rules.ParamHazardDamagePerTurn: "12",
-				rules.ParamHazardMap:           "test",
-				rules.ParamHazardMapAuthor:     "tester",
 			})
 
-			require.NotNil(t, rsb.Ruleset())
+			require.NotNil(t, rsb.NamedRuleset(expected.GameType))
-			require.Equal(t, expected.GameType, rsb.Ruleset().Name())
+			require.Equal(t, expected.GameType, rsb.NamedRuleset(expected.GameType).Name())
 			// All the standard settings should always be copied over
-			require.Equal(t, 10, rsb.Ruleset().Settings().FoodSpawnChance)
+			require.Equal(t, 10, rsb.NamedRuleset(expected.GameType).Settings().Int(rules.ParamFoodSpawnChance, 0))
-			require.Equal(t, 12, rsb.Ruleset().Settings().HazardDamagePerTurn)
+			require.Equal(t, 12, rsb.NamedRuleset(expected.GameType).Settings().Int(rules.ParamHazardDamagePerTurn, 0))
-			require.Equal(t, 5, rsb.Ruleset().Settings().MinimumFood)
+			require.Equal(t, 5, rsb.NamedRuleset(expected.GameType).Settings().Int(rules.ParamMinimumFood, 0))
-			require.Equal(t, "test", rsb.Ruleset().Settings().HazardMap)
-			require.Equal(t, "tester", rsb.Ruleset().Settings().HazardMapAuthor)
 		})
 	}
 }
 
 func TestRulesetBuilderGameOver(t *testing.T) {
-	settings := rules.Settings{
+	settings := rules.NewSettingsWithParams(rules.ParamShrinkEveryNTurns, "12")
-		RoyaleSettings: rules.RoyaleSettings{
-			ShrinkEveryNTurns: 12,
-		},
-	}
 	moves := []rules.SnakeMove{
 		{ID: "1", Move: "up"},
 	}
@@ -214,13 +116,11 @@ func TestRulesetBuilderGameOver(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(fmt.Sprintf("%v_%v", test.gameType, test.solo), func(t *testing.T) {
-			rsb := rules.NewRulesetBuilder().WithParams(map[string]string{
+			rsb := rules.NewRulesetBuilder().WithSettings(settings).WithSolo(test.solo)
-				rules.ParamGameType: test.gameType,
-			}).WithSolo(test.solo)
 
-			ruleset := rsb.Ruleset()
+			ruleset := rsb.NamedRuleset(test.gameType)
 
-			gameOver, _, err := ruleset.Execute(boardState, settings, moves)
+			gameOver, _, err := ruleset.Execute(boardState, moves)
 
 			require.NoError(t, err)
 			require.Equal(t, test.gameOver, gameOver)
@@ -234,7 +134,7 @@ func TestStageFuncContract(t *testing.T) {
 	stage = func(bs *rules.BoardState, s rules.Settings, sm []rules.SnakeMove) (bool, error) {
 		return true, nil
 	}
-	ended, err := stage(nil, rules.NewRulesetBuilder().Ruleset().Settings(), nil)
+	ended, err := stage(nil, rules.NewRulesetBuilder().NamedRuleset("").Settings(), nil)
 	require.NoError(t, err)
 	require.True(t, ended)
 }

settings.go

@@ -0,0 +1,90 @@
+package rules
+
+import "strconv"
+
+// Settings contains all settings relevant to a game.
+// The settings are stored as raw string values, which should not be accessed
+// directly. Calling code should instead use the Int/Bool methods to parse them.
+type Settings struct {
+	rawValues map[string]string
+
+	rand Rand
+	seed int64
+}
+
+func NewSettings(params map[string]string) Settings {
+	rawValues := make(map[string]string, len(params))
+
+	// Copy incoming params into a new map
+	for key, value := range params {
+		rawValues[key] = value
+	}
+
+	return Settings{
+		rawValues: rawValues,
+	}
+}
+
+func NewSettingsWithParams(params ...string) Settings {
+	rawValues := map[string]string{}
+
+	for index := 1; index < len(params); index += 2 {
+		rawValues[params[index-1]] = params[index]
+	}
+
+	return Settings{
+		rawValues: rawValues,
+	}
+}
+
+// Get a random number generator initialized based on the seed and current turn.
+func (settings Settings) GetRand(turn int) Rand {
+	// Allow overriding the random generator for testing
+	if settings.rand != nil {
+		return settings.rand
+	}
+
+	if settings.seed != 0 {
+		return NewSeedRand(settings.seed + int64(turn))
+	}
+
+	// Default to global random number generator if neither seed or rand are set.
+	return GlobalRand
+}
+
+func (settings Settings) WithRand(rand Rand) Settings {
+	settings.rand = rand
+	return settings
+}
+
+func (settings Settings) Seed() int64 {
+	return settings.seed
+}
+
+func (settings Settings) WithSeed(seed int64) Settings {
+	settings.seed = seed
+	return settings
+}
+
+// Bool returns the boolean value for the specified parameter.
+// If the parameter doesn't exist, the default value will be returned.
+// If the parameter does exist, but is not "true", false will be returned.
+func (settings Settings) Bool(paramName string, defaultValue bool) bool {
+	if val, ok := settings.rawValues[paramName]; ok {
+		return val == "true"
+	}
+	return defaultValue
+}
+
+// Int returns the int value for the specified parameter.
+// If the parameter doesn't exist, the default value will be returned.
+// If the parameter does exist, but is not a valid int, the default value will be returned.
+func (settings Settings) Int(paramName string, defaultValue int) int {
+	if val, ok := settings.rawValues[paramName]; ok {
+		i, err := strconv.Atoi(val)
+		if err == nil {
+			return i
+		}
+	}
+	return defaultValue
+}

settings_test.go

@@ -0,0 +1,31 @@
+package rules_test
+
+import (
+	"testing"
+
+	"github.com/BattlesnakeOfficial/rules"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSettings(t *testing.T) {
+	params := map[string]string{
+		"invalidSetting": "abcd",
+		"intSetting":     "1234",
+		"boolSetting":    "true",
+	}
+
+	settings := rules.NewSettings(params)
+
+	assert.Equal(t, 4567, settings.Int("missingIntSetting", 4567))
+	assert.Equal(t, 4567, settings.Int("invalidSetting", 4567))
+	assert.Equal(t, 1234, settings.Int("intSetting", 4567))
+
+	assert.Equal(t, false, settings.Bool("missingBoolSetting", false))
+	assert.Equal(t, true, settings.Bool("missingBoolSetting", true))
+	assert.Equal(t, false, settings.Bool("invalidSetting", true))
+	assert.Equal(t, true, settings.Bool("boolSetting", true))
+
+	assert.Equal(t, 4567, rules.NewSettingsWithParams("newIntSetting").Int("newIntSetting", 4567))
+	assert.Equal(t, 1234, rules.NewSettingsWithParams("newIntSetting", "1234").Int("newIntSetting", 4567))
+	assert.Equal(t, 4567, rules.NewSettingsWithParams("x", "y", "newIntSetting").Int("newIntSetting", 4567))
+}

solo.go

@@ -9,25 +9,6 @@ var soloRulesetStages = []string{
 	StageEliminationStandard,
 }
 
-type SoloRuleset struct {
-	StandardRuleset
-}
-
-func (r *SoloRuleset) Name() string { return GameTypeSolo }
-
-func (r SoloRuleset) Execute(bs *BoardState, s Settings, sm []SnakeMove) (bool, *BoardState, error) {
-	return NewPipeline(soloRulesetStages...).Execute(bs, s, sm)
-}
-
-func (r *SoloRuleset) CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
-	_, nextState, err := r.Execute(prevState, r.Settings(), moves)
-	return nextState, err
-}
-
-func (r *SoloRuleset) IsGameOver(b *BoardState) (bool, error) {
-	return GameOverSolo(b, r.Settings(), nil)
-}
-
 func GameOverSolo(b *BoardState, settings Settings, moves []SnakeMove) (bool, error) {
 	for i := 0; i < len(b.Snakes); i++ {
 		if b.Snakes[i].EliminatedCause == NotEliminated {

solo_test.go

@@ -6,20 +6,21 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestSoloRulesetInterface(t *testing.T) {
+func getSoloRuleset(settings Settings) Ruleset {
-	var _ Ruleset = (*SoloRuleset)(nil)
+	return NewRulesetBuilder().WithSettings(settings).NamedRuleset(GameTypeSolo)
 }
 
 func TestSoloName(t *testing.T) {
-	r := SoloRuleset{}
+	r := getSoloRuleset(Settings{})
 	require.Equal(t, "solo", r.Name())
 }
 
 func TestSoloCreateNextBoardStateSanity(t *testing.T) {
 	boardState := &BoardState{}
-	r := SoloRuleset{}
+	r := getSoloRuleset(Settings{})
-	_, err := r.CreateNextBoardState(boardState, []SnakeMove{})
+	gameOver, _, err := r.Execute(boardState, []SnakeMove{})
 	require.NoError(t, err)
+	require.True(t, gameOver)
 }
 
 func TestSoloIsGameOver(t *testing.T) {
@@ -41,7 +42,7 @@ func TestSoloIsGameOver(t *testing.T) {
 		},
 	}
 
-	r := SoloRuleset{}
+	r := getSoloRuleset(Settings{})
 	for _, test := range tests {
 		b := &BoardState{
 			Height: 11,
@@ -50,7 +51,7 @@ func TestSoloIsGameOver(t *testing.T) {
 			Food:   []Point{},
 		}
 
-		actual, err := r.IsGameOver(b)
+		actual, _, err := r.Execute(b, nil)
 		require.NoError(t, err)
 		require.Equal(t, test.Expected, actual)
 	}
@@ -69,11 +70,11 @@ var soloCaseNotOver = gameTestCase{
 		Snakes: []Snake{
 			{
 				ID:     "one",
-				Body:   []Point{{1, 1}, {1, 2}},
+				Body:   []Point{{X: 1, Y: 1}, {X: 1, Y: 2}},
 				Health: 100,
 			},
 		},
-		Food:    []Point{{0, 0}, {1, 0}},
+		Food:    []Point{{X: 0, Y: 0}, {X: 1, Y: 0}},
 		Hazards: []Point{},
 	},
 	[]SnakeMove{
@@ -86,11 +87,11 @@ var soloCaseNotOver = gameTestCase{
 		Snakes: []Snake{
 			{
 				ID:     "one",
-				Body:   []Point{{1, 0}, {1, 1}, {1, 1}},
+				Body:   []Point{{X: 1, Y: 0}, {X: 1, Y: 1}, {X: 1, Y: 1}},
 				Health: 100,
 			},
 		},
-		Food:    []Point{{0, 0}},
+		Food:    []Point{{X: 0, Y: 0}},
 		Hazards: []Point{},
 	},
 }
@@ -104,14 +105,10 @@ func TestSoloCreateNextBoardState(t *testing.T) {
 		standardMoveAndCollideMAD,
 		soloCaseNotOver,
 	}
-	r := SoloRuleset{}
+	r := getSoloRuleset(Settings{})
-	rb := NewRulesetBuilder().WithParams(map[string]string{
-		ParamGameType: GameTypeSolo,
-	})
 	for _, gc := range cases {
-		gc.requireValidNextState(t, &r)
+		// test a RulesBuilder constructed instance
-		// also test a RulesBuilder constructed instance
+		gc.requireValidNextState(t, r)
-		gc.requireValidNextState(t, rb.Ruleset())
 		// also test a pipeline with the same settings
 		gc.requireValidNextState(t, NewRulesetBuilder().PipelineRuleset(GameTypeSolo, NewPipeline(soloRulesetStages...)))
 	}
@@ -119,26 +116,18 @@ func TestSoloCreateNextBoardState(t *testing.T) {
 
 // Test a snake running right into the wall is properly eliminated
 func TestSoloEliminationOutOfBounds(t *testing.T) {
-	r := SoloRuleset{}
+	r := getSoloRuleset(Settings{})
 
 	// Using MaxRand is important because it ensures that the snakes are consistently placed in a way this test will work.
 	// Actually random placement could result in the assumptions made by this test being incorrect.
 	initialState, err := CreateDefaultBoardState(MaxRand, 2, 2, []string{"one"})
 	require.NoError(t, err)
 
-	_, next, err := r.Execute(
+	_, next, err := r.Execute(initialState, []SnakeMove{{ID: "one", Move: "right"}})
-		initialState,
-		r.Settings(),
-		[]SnakeMove{{ID: "one", Move: "right"}},
-	)
 	require.NoError(t, err)
 	require.NotNil(t, initialState)
 
-	ended, next, err := r.Execute(
+	ended, next, err := r.Execute(next, []SnakeMove{{ID: "one", Move: "right"}})
-		next,
-		r.Settings(),
-		[]SnakeMove{{ID: "one", Move: "right"}},
-	)
 	require.NoError(t, err)
 	require.NotNil(t, initialState)
 

standard.go

@@ -5,14 +5,6 @@ import (
 	"sort"
 )
 
-type StandardRuleset struct {
-	FoodSpawnChance     int // [0, 100]
-	MinimumFood         int
-	HazardDamagePerTurn int
-	HazardMap           string // optional
-	HazardMapAuthor     string // optional
-}
-
 var standardRulesetStages = []string{
 	StageGameOverStandard,
 	StageMovementStandard,
@@ -22,23 +14,6 @@ var standardRulesetStages = []string{
 	StageEliminationStandard,
 }
 
-func (r *StandardRuleset) Name() string { return GameTypeStandard }
-
-func (r *StandardRuleset) ModifyInitialBoardState(initialState *BoardState) (*BoardState, error) {
-	// No-op
-	return initialState, nil
-}
-
-// impl Pipeline
-func (r StandardRuleset) Execute(bs *BoardState, s Settings, sm []SnakeMove) (bool, *BoardState, error) {
-	return NewPipeline(standardRulesetStages...).Execute(bs, s, sm)
-}
-
-func (r *StandardRuleset) CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
-	_, nextState, err := r.Execute(prevState, r.Settings(), moves)
-	return nextState, err
-}
-
 func MoveSnakesStandard(b *BoardState, settings Settings, moves []SnakeMove) (bool, error) {
 	if IsInitialization(b, settings, moves) {
 		return false, nil
@@ -156,6 +131,7 @@ func DamageHazardsStandard(b *BoardState, settings Settings, moves []SnakeMove)
 	if IsInitialization(b, settings, moves) {
 		return false, nil
 	}
+	hazardDamage := settings.Int(ParamHazardDamagePerTurn, 0)
 	for i := 0; i < len(b.Snakes); i++ {
 		snake := &b.Snakes[i]
 		if snake.EliminatedCause != NotEliminated {
@@ -176,7 +152,7 @@ func DamageHazardsStandard(b *BoardState, settings Settings, moves []SnakeMove)
 				}
 
 				// Snake is in a hazard, reduce health
-				snake.Health = snake.Health - settings.HazardDamagePerTurn
+				snake.Health = snake.Health - hazardDamage
 				if snake.Health < 0 {
 					snake.Health = 0
 				}
@@ -393,20 +369,18 @@ func SpawnFoodStandard(b *BoardState, settings Settings, moves []SnakeMove) (boo
 	if IsInitialization(b, settings, moves) {
 		return false, nil
 	}
+	minimumFood := settings.Int(ParamMinimumFood, 0)
+	foodSpawnChance := settings.Int(ParamFoodSpawnChance, 0)
 	numCurrentFood := int(len(b.Food))
-	if numCurrentFood < settings.MinimumFood {
+	if numCurrentFood < minimumFood {
-		return false, PlaceFoodRandomly(GlobalRand, b, settings.MinimumFood-numCurrentFood)
+		return false, PlaceFoodRandomly(GlobalRand, b, minimumFood-numCurrentFood)
 	}
-	if settings.FoodSpawnChance > 0 && int(rand.Intn(100)) < settings.FoodSpawnChance {
+	if foodSpawnChance > 0 && int(rand.Intn(100)) < foodSpawnChance {
 		return false, PlaceFoodRandomly(GlobalRand, b, 1)
 	}
 	return false, nil
 }
 
-func (r *StandardRuleset) IsGameOver(b *BoardState) (bool, error) {
-	return GameOverStandard(b, r.Settings(), nil)
-}
-
 func GameOverStandard(b *BoardState, settings Settings, moves []SnakeMove) (bool, error) {
 	numSnakesRemaining := 0
 	for i := 0; i < len(b.Snakes); i++ {
@@ -416,25 +390,3 @@ func GameOverStandard(b *BoardState, settings Settings, moves []SnakeMove) (bool
 	}
 	return numSnakesRemaining <= 1, nil
 }
-
-func (r StandardRuleset) Settings() Settings {
-	return Settings{
-		FoodSpawnChance:     r.FoodSpawnChance,
-		MinimumFood:         r.MinimumFood,
-		HazardDamagePerTurn: r.HazardDamagePerTurn,
-		HazardMap:           r.HazardMap,
-		HazardMapAuthor:     r.HazardMapAuthor,
-	}
-}
-
-// impl Pipeline
-func (r StandardRuleset) Err() error {
-	return nil
-}
-
-// IsInitialization checks whether the current state means the game is initialising.
-func IsInitialization(b *BoardState, settings Settings, moves []SnakeMove) bool {
-	// We can safely assume that the game state is in the initialisation phase when
-	// the turn hasn't advanced and the moves are empty
-	return b.Turn <= 0 && len(moves) == 0
-}

wrapped.go

@@ -9,22 +9,6 @@ var wrappedRulesetStages = []string{
 	StageEliminationStandard,
 }
 
-type WrappedRuleset struct {
-	StandardRuleset
-}
-
-func (r *WrappedRuleset) Name() string { return GameTypeWrapped }
-
-func (r WrappedRuleset) Execute(bs *BoardState, s Settings, sm []SnakeMove) (bool, *BoardState, error) {
-	return NewPipeline(wrappedRulesetStages...).Execute(bs, s, sm)
-}
-
-func (r *WrappedRuleset) CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error) {
-	_, nextState, err := r.Execute(prevState, r.Settings(), moves)
-
-	return nextState, err
-}
-
 func MoveSnakesWrapped(b *BoardState, settings Settings, moves []SnakeMove) (bool, error) {
 	if IsInitialization(b, settings, moves) {
 		return false, nil
@@ -47,10 +31,6 @@ func MoveSnakesWrapped(b *BoardState, settings Settings, moves []SnakeMove) (boo
 	return false, nil
 }
 
-func (r *WrappedRuleset) IsGameOver(b *BoardState) (bool, error) {
-	return GameOverStandard(b, r.Settings(), nil)
-}
-
 func wrap(value, min, max int) int {
 	if value < min {
 		return max

wrapped_test.go

@@ -7,15 +7,19 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func getWrappedRuleset(settings Settings) Ruleset {
+	return NewRulesetBuilder().WithSettings(settings).NamedRuleset(GameTypeWrapped)
+}
+
 func TestLeft(t *testing.T) {
 	boardState := &BoardState{
 		Width:  11,
 		Height: 11,
 		Snakes: []Snake{
-			{ID: "bottomLeft", Health: 10, Body: []Point{{0, 0}}},
+			{ID: "bottomLeft", Health: 10, Body: []Point{{X: 0, Y: 0}}},
-			{ID: "bottomRight", Health: 10, Body: []Point{{10, 0}}},
+			{ID: "bottomRight", Health: 10, Body: []Point{{X: 10, Y: 0}}},
-			{ID: "topLeft", Health: 10, Body: []Point{{0, 10}}},
+			{ID: "topLeft", Health: 10, Body: []Point{{X: 0, Y: 10}}},
-			{ID: "topRight", Health: 10, Body: []Point{{10, 10}}},
+			{ID: "topRight", Health: 10, Body: []Point{{X: 10, Y: 10}}},
 		},
 	}
 
@@ -26,17 +30,18 @@ func TestLeft(t *testing.T) {
 		{ID: "topRight", Move: "left"},
 	}
 
-	r := WrappedRuleset{}
+	r := getWrappedRuleset(Settings{})
 
-	nextBoardState, err := r.CreateNextBoardState(boardState, snakeMoves)
+	gameOver, nextBoardState, err := r.Execute(boardState, snakeMoves)
 	require.NoError(t, err)
+	require.False(t, gameOver)
 	require.Equal(t, len(boardState.Snakes), len(nextBoardState.Snakes))
 
 	expectedSnakes := []Snake{
-		{ID: "bottomLeft", Health: 10, Body: []Point{{10, 0}}},
+		{ID: "bottomLeft", Health: 10, Body: []Point{{X: 10, Y: 0}}},
-		{ID: "bottomRight", Health: 10, Body: []Point{{9, 0}}},
+		{ID: "bottomRight", Health: 10, Body: []Point{{X: 9, Y: 0}}},
-		{ID: "topLeft", Health: 10, Body: []Point{{10, 10}}},
+		{ID: "topLeft", Health: 10, Body: []Point{{X: 10, Y: 10}}},
-		{ID: "topRight", Health: 10, Body: []Point{{9, 10}}},
+		{ID: "topRight", Health: 10, Body: []Point{{X: 9, Y: 10}}},
 	}
 	for i, snake := range nextBoardState.Snakes {
 		require.Equal(t, expectedSnakes[i].ID, snake.ID, snake.ID)
@@ -51,10 +56,10 @@ func TestRight(t *testing.T) {
 		Width:  11,
 		Height: 11,
 		Snakes: []Snake{
-			{ID: "bottomLeft", Health: 10, Body: []Point{{0, 0}}},
+			{ID: "bottomLeft", Health: 10, Body: []Point{{X: 0, Y: 0}}},
-			{ID: "bottomRight", Health: 10, Body: []Point{{10, 0}}},
+			{ID: "bottomRight", Health: 10, Body: []Point{{X: 10, Y: 0}}},
-			{ID: "topLeft", Health: 10, Body: []Point{{0, 10}}},
+			{ID: "topLeft", Health: 10, Body: []Point{{X: 0, Y: 10}}},
-			{ID: "topRight", Health: 10, Body: []Point{{10, 10}}},
+			{ID: "topRight", Health: 10, Body: []Point{{X: 10, Y: 10}}},
 		},
 	}
 
@@ -65,17 +70,18 @@ func TestRight(t *testing.T) {
 		{ID: "topRight", Move: "right"},
 	}
 
-	r := WrappedRuleset{}
+	r := getWrappedRuleset(Settings{})
 
-	nextBoardState, err := r.CreateNextBoardState(boardState, snakeMoves)
+	gameOver, nextBoardState, err := r.Execute(boardState, snakeMoves)
 	require.NoError(t, err)
+	require.False(t, gameOver)
 	require.Equal(t, len(boardState.Snakes), len(nextBoardState.Snakes))
 
 	expectedSnakes := []Snake{
-		{ID: "bottomLeft", Health: 10, Body: []Point{{1, 0}}},
+		{ID: "bottomLeft", Health: 10, Body: []Point{{X: 1, Y: 0}}},
-		{ID: "bottomRight", Health: 10, Body: []Point{{0, 0}}},
+		{ID: "bottomRight", Health: 10, Body: []Point{{X: 0, Y: 0}}},
-		{ID: "topLeft", Health: 10, Body: []Point{{1, 10}}},
+		{ID: "topLeft", Health: 10, Body: []Point{{X: 1, Y: 10}}},
-		{ID: "topRight", Health: 10, Body: []Point{{0, 10}}},
+		{ID: "topRight", Health: 10, Body: []Point{{X: 0, Y: 10}}},
 	}
 	for i, snake := range nextBoardState.Snakes {
 		require.Equal(t, expectedSnakes[i].ID, snake.ID, snake.ID)
@@ -90,10 +96,10 @@ func TestUp(t *testing.T) {
 		Width:  11,
 		Height: 11,
 		Snakes: []Snake{
-			{ID: "bottomLeft", Health: 10, Body: []Point{{0, 0}}},
+			{ID: "bottomLeft", Health: 10, Body: []Point{{X: 0, Y: 0}}},
-			{ID: "bottomRight", Health: 10, Body: []Point{{10, 0}}},
+			{ID: "bottomRight", Health: 10, Body: []Point{{X: 10, Y: 0}}},
-			{ID: "topLeft", Health: 10, Body: []Point{{0, 10}}},
+			{ID: "topLeft", Health: 10, Body: []Point{{X: 0, Y: 10}}},
-			{ID: "topRight", Health: 10, Body: []Point{{10, 10}}},
+			{ID: "topRight", Health: 10, Body: []Point{{X: 10, Y: 10}}},
 		},
 	}
 
@@ -104,17 +110,18 @@ func TestUp(t *testing.T) {
 		{ID: "topRight", Move: "up"},
 	}
 
-	r := WrappedRuleset{}
+	r := getWrappedRuleset(Settings{})
 
-	nextBoardState, err := r.CreateNextBoardState(boardState, snakeMoves)
+	gameOver, nextBoardState, err := r.Execute(boardState, snakeMoves)
 	require.NoError(t, err)
+	require.False(t, gameOver)
 	require.Equal(t, len(boardState.Snakes), len(nextBoardState.Snakes))
 
 	expectedSnakes := []Snake{
-		{ID: "bottomLeft", Health: 10, Body: []Point{{0, 1}}},
+		{ID: "bottomLeft", Health: 10, Body: []Point{{X: 0, Y: 1}}},
-		{ID: "bottomRight", Health: 10, Body: []Point{{10, 1}}},
+		{ID: "bottomRight", Health: 10, Body: []Point{{X: 10, Y: 1}}},
-		{ID: "topLeft", Health: 10, Body: []Point{{0, 0}}},
+		{ID: "topLeft", Health: 10, Body: []Point{{X: 0, Y: 0}}},
-		{ID: "topRight", Health: 10, Body: []Point{{10, 0}}},
+		{ID: "topRight", Health: 10, Body: []Point{{X: 10, Y: 0}}},
 	}
 	for i, snake := range nextBoardState.Snakes {
 		require.Equal(t, expectedSnakes[i].ID, snake.ID, snake.ID)
@@ -129,10 +136,10 @@ func TestDown(t *testing.T) {
 		Width:  11,
 		Height: 11,
 		Snakes: []Snake{
-			{ID: "bottomLeft", Health: 10, Body: []Point{{0, 0}}},
+			{ID: "bottomLeft", Health: 10, Body: []Point{{X: 0, Y: 0}}},
-			{ID: "bottomRight", Health: 10, Body: []Point{{10, 0}}},
+			{ID: "bottomRight", Health: 10, Body: []Point{{X: 10, Y: 0}}},
-			{ID: "topLeft", Health: 10, Body: []Point{{0, 10}}},
+			{ID: "topLeft", Health: 10, Body: []Point{{X: 0, Y: 10}}},
-			{ID: "topRight", Health: 10, Body: []Point{{10, 10}}},
+			{ID: "topRight", Health: 10, Body: []Point{{X: 10, Y: 10}}},
 		},
 	}
 
@@ -143,17 +150,18 @@ func TestDown(t *testing.T) {
 		{ID: "topRight", Move: "down"},
 	}
 
-	r := WrappedRuleset{}
+	r := getWrappedRuleset(Settings{})
 
-	nextBoardState, err := r.CreateNextBoardState(boardState, snakeMoves)
+	gameOver, nextBoardState, err := r.Execute(boardState, snakeMoves)
 	require.NoError(t, err)
+	require.False(t, gameOver)
 	require.Equal(t, len(boardState.Snakes), len(nextBoardState.Snakes))
 
 	expectedSnakes := []Snake{
-		{ID: "bottomLeft", Health: 10, Body: []Point{{0, 10}}},
+		{ID: "bottomLeft", Health: 10, Body: []Point{{X: 0, Y: 10}}},
-		{ID: "bottomRight", Health: 10, Body: []Point{{10, 10}}},
+		{ID: "bottomRight", Health: 10, Body: []Point{{X: 10, Y: 10}}},
-		{ID: "topLeft", Health: 10, Body: []Point{{0, 9}}},
+		{ID: "topLeft", Health: 10, Body: []Point{{X: 0, Y: 9}}},
-		{ID: "topRight", Health: 10, Body: []Point{{10, 9}}},
+		{ID: "topRight", Health: 10, Body: []Point{{X: 10, Y: 9}}},
 	}
 	for i, snake := range nextBoardState.Snakes {
 		require.Equal(t, expectedSnakes[i].ID, snake.ID, snake.ID)
@@ -168,14 +176,14 @@ func TestEdgeCrossingCollision(t *testing.T) {
 		Width:  11,
 		Height: 11,
 		Snakes: []Snake{
-			{ID: "left", Health: 10, Body: []Point{{0, 5}}},
+			{ID: "left", Health: 10, Body: []Point{{X: 0, Y: 5}}},
 			{ID: "rightEdge", Health: 10, Body: []Point{
-				{10, 1},
+				{X: 10, Y: 1},
-				{10, 2},
+				{X: 10, Y: 2},
-				{10, 3},
+				{X: 10, Y: 3},
-				{10, 4},
+				{X: 10, Y: 4},
-				{10, 5},
+				{X: 10, Y: 5},
-				{10, 6},
+				{X: 10, Y: 6},
 			}},
 		},
 	}
@@ -185,21 +193,22 @@ func TestEdgeCrossingCollision(t *testing.T) {
 		{ID: "rightEdge", Move: "down"},
 	}
 
-	r := WrappedRuleset{}
+	r := getWrappedRuleset(Settings{})
 
-	nextBoardState, err := r.CreateNextBoardState(boardState, snakeMoves)
+	gameOver, nextBoardState, err := r.Execute(boardState, snakeMoves)
 	require.NoError(t, err)
+	require.False(t, gameOver)
 	require.Equal(t, len(boardState.Snakes), len(nextBoardState.Snakes))
 
 	expectedSnakes := []Snake{
-		{ID: "left", Health: 0, Body: []Point{{10, 5}}, EliminatedCause: EliminatedByCollision, EliminatedBy: "rightEdge"},
+		{ID: "left", Health: 0, Body: []Point{{X: 10, Y: 5}}, EliminatedCause: EliminatedByCollision, EliminatedBy: "rightEdge"},
 		{ID: "rightEdge", Health: 10, Body: []Point{
-			{10, 0},
+			{X: 10, Y: 0},
-			{10, 1},
+			{X: 10, Y: 1},
-			{10, 2},
+			{X: 10, Y: 2},
-			{10, 3},
+			{X: 10, Y: 3},
-			{10, 4},
+			{X: 10, Y: 4},
-			{10, 5},
+			{X: 10, Y: 5},
 		}},
 	}
 	for i, snake := range nextBoardState.Snakes {
@@ -215,11 +224,11 @@ func TestEdgeCrossingEating(t *testing.T) {
 		Width:  11,
 		Height: 11,
 		Snakes: []Snake{
-			{ID: "left", Health: 10, Body: []Point{{0, 5}, {1, 5}}},
+			{ID: "left", Health: 10, Body: []Point{{X: 0, Y: 5}, {X: 1, Y: 5}}},
-			{ID: "other", Health: 10, Body: []Point{{5, 5}}},
+			{ID: "other", Health: 10, Body: []Point{{X: 5, Y: 5}}},
 		},
 		Food: []Point{
-			{10, 5},
+			{X: 10, Y: 5},
 		},
 	}
 
@@ -228,15 +237,16 @@ func TestEdgeCrossingEating(t *testing.T) {
 		{ID: "other", Move: "left"},
 	}
 
-	r := WrappedRuleset{}
+	r := getWrappedRuleset(Settings{})
 
-	nextBoardState, err := r.CreateNextBoardState(boardState, snakeMoves)
+	gameOver, nextBoardState, err := r.Execute(boardState, snakeMoves)
 	require.NoError(t, err)
+	require.False(t, gameOver)
 	require.Equal(t, len(boardState.Snakes), len(nextBoardState.Snakes))
 
 	expectedSnakes := []Snake{
-		{ID: "left", Health: 100, Body: []Point{{10, 5}, {0, 5}, {0, 5}}},
+		{ID: "left", Health: 100, Body: []Point{{X: 10, Y: 5}, {X: 0, Y: 5}, {X: 0, Y: 5}}},
-		{ID: "other", Health: 9, Body: []Point{{4, 5}}},
+		{ID: "other", Health: 9, Body: []Point{{X: 4, Y: 5}}},
 	}
 	for i, snake := range nextBoardState.Snakes {
 		require.Equal(t, expectedSnakes[i].ID, snake.ID, snake.ID)
@@ -271,12 +281,12 @@ var wrappedCaseMoveAndWrap = gameTestCase{
 		Snakes: []Snake{
 			{
 				ID:     "one",
-				Body:   []Point{{0, 0}, {1, 0}},
+				Body:   []Point{{X: 0, Y: 0}, {X: 1, Y: 0}},
 				Health: 100,
 			},
 			{
 				ID:     "two",
-				Body:   []Point{{3, 4}, {3, 3}},
+				Body:   []Point{{X: 3, Y: 4}, {X: 3, Y: 3}},
 				Health: 100,
 			},
 			{
@@ -301,12 +311,12 @@ var wrappedCaseMoveAndWrap = gameTestCase{
 		Snakes: []Snake{
 			{
 				ID:     "one",
-				Body:   []Point{{9, 0}, {0, 0}},
+				Body:   []Point{{X: 9, Y: 0}, {X: 0, Y: 0}},
 				Health: 99,
 			},
 			{
 				ID:     "two",
-				Body:   []Point{{3, 5}, {3, 4}},
+				Body:   []Point{{X: 3, Y: 5}, {X: 3, Y: 4}},
 				Health: 99,
 			},
 			{
@@ -330,14 +340,10 @@ func TestWrappedCreateNextBoardState(t *testing.T) {
 		standardMoveAndCollideMAD,
 		wrappedCaseMoveAndWrap,
 	}
-	r := WrappedRuleset{}
+	r := getWrappedRuleset(Settings{})
-	rb := NewRulesetBuilder().WithParams(map[string]string{
-		ParamGameType: GameTypeWrapped,
-	})
 	for _, gc := range cases {
-		gc.requireValidNextState(t, &r)
+		// test a RulesBuilder constructed instance
-		// also test a RulesBuilder constructed instance
+		gc.requireValidNextState(t, r)
-		gc.requireValidNextState(t, rb.Ruleset())
 		// also test a pipeline with the same settings
 		gc.requireValidNextState(t, NewRulesetBuilder().PipelineRuleset(GameTypeWrapped, NewPipeline(wrappedRulesetStages...)))
 	}