--- title: "Traffic release puzzles: API" package: "@phaser-ae/traffic-release" tier: Pro version: 3.0.0-3 released: 2026-10-14 updated: 2026-10-19 description: "The rules and seeded level generator for tap-to-release puzzles, where a car or block leaves only when its whole route off the board is clear, flat or in 3D." url: https://phaser.io/packs/traffic-release/api site: Phaser - https://phaser.io --- # Traffic release puzzles: API `@phaser-ae/traffic-release` — Release cars or 3D voxel blocks along routes that must be clear, with seeded screened levels, hazards and undo, as in Tap Away and Traffic Escape. ## The pack ### `trafficRelease` ```ts function trafficRelease(): Pack<{ trafficRelease: TrafficReleaseApi }> ``` Install pure rules; no renderer, DOM or simulation hook is required. ## Helpers ### `createTrafficRelease` ```ts const createTrafficRelease = (config: TrafficConfig, solution?: TrafficAction[])=> … ``` Create a traffic puzzle. Throws on a configuration it refuses (out-of-range sizes, overlaps, a route that does not start at its piece, jumps or does not leave the board) or a `solution` that does not replay to a win. ### `generateTrafficRelease` ```ts function generateTrafficRelease(options: TrafficGenerateOptions): TrafficLevel ``` Generate a seeded level whose solution is replayed before it is returned. Candidates are tried until one has at most `maxInitialChoices` open routes and a blocking chain at least `minDependencyDepth` long; throws `generation: no ... level met ...` when `attempts` run out, and on out-of-range options. ### `straightTrafficRoute` ```ts function straightTrafficRoute(cells: Voxel[], direction: Voxel, bounds: Pick, id = 'exit'): TrafficRoute ``` A straight route for `cells`: one step at a time along `direction` (a unit axis such as `{ x: 1, y: 0, z: 0 }`) until wholly outside `bounds`. Throws on any other direction or a route longer than 64 steps. ## Classes ### `TrafficRelease` ```ts class TrafficRelease ``` A traffic puzzle's rules, with undo, redo and a solver. Get one from `createTrafficRelease`. - `constructor(config: TrafficConfig, solution: TrafficAction[] = [])` - `get config(): TrafficConfig` — A copy of the configuration. - `get state(): TrafficState` — A copy of the current state. - `get solved(): boolean` — True when every piece has left the board. - `get lost(): boolean` — True when `maxMistakes` blocked releases have been made with pieces still on the board. A release-only puzzle has no other way to lose. - `cells(id: string): Voxel[]` — The cells piece `id` covers now (part way along its route if it is moving); empty once it has left or for an unknown id. - `hazardCells(): { id: string; cells: Voxel[]; }[]` — Where each hazard is at the current tick. - `inspect(id: string, route: string): TrafficClearance` — What stands in the way of piece `id` leaving by `route` now, step by step; changes nothing. - `preview(a: TrafficAction): ActionResult` — What `apply` would return for `a`, without playing it; never costs a mistake. - `apply(a: TrafficAction): ActionResult` — Play a move. Returns `{ valid: true, events }`, or `{ valid: false, reason, events: [] }` with a reason: `blocked`, `reserved-lane`, `hazard`, `already-moving`, `unknown-piece`, `unknown-route` or `mistake-limit`. A blocked release counts as a mistake (and goes in the history) when `maxMistakes` is set. - `legalActions(): TrafficAction[]` — Every release that is clear now, then `{ type: 'tick' }` while the puzzle is unsolved. - `solve(maxStates = 20000): SearchResult` — A winning continuation, without changing anything: the rest of the creation certificate when it still applies, otherwise a greedy plan (release the first clear piece, else wait a tick). Greedy is exact here: a piece that leaves never blocks anything again, so no release can spoil the puzzle. `unsolvable` after 120 idle ticks or at the mistake limit; `budget-exhausted` after `maxStates` steps (default 20,000). - `undo(): boolean` — Take back the last move (a tick, a release or a mistake); false when there is none. - `redo(): boolean` — Replay the move last taken back; false when there is none. - `reset(): void` — Return to the start and clear the undo and redo history. ## Types ### `TrafficAction` ```ts type TrafficAction = { type: 'release'; id: string; route: string; } | { type: 'tick'; } ``` A move: release piece `id` along its route `route`, or let one tick of time pass (moving pieces advance a step, hazards a phase). ### `TrafficClearance` ```ts interface TrafficClearance ``` What stands in a route's way, from `inspect`. - `clear: boolean` — True when nothing does: the piece can be released by this route now. - `blockers: { /** A parked \`piece\`, a \`wall\`, a moving piece's \`reservation\` or a \`hazard\` at the tick of that step. */ kind: 'piece' | 'wall' | 'reservation' | 'hazard'; /** The blocking piece's or hazard's id; \`'wall'\` for a wall. */ id: string; /** The cell where it blocks. */ cell: Voxel; /** The route step (footprint index) that meets it. */ frame: number; }[]` — Everything in the way, by route step. - `swept: Voxel[]` — Every cell the route sweeps, corners of turns included: what a presenter highlights. ### `TrafficConfig` ```ts interface TrafficConfig ``` A level: the board's size, the pieces and their routes, and optional walls, hazards and a mistake limit. - `width: number` — Cells across, 1 to 24. - `height: number` — Cells deep (rows of a flat board), 1 to 24. - `depth: number` — Cells high, 1 to 24; 1 for a flat board. - `pieces: TrafficPiece[]` — The pieces, 1 to 256, with unique ids and no shared cells. - `walls?: Voxel[]` — Cells that are always blocked (barriers, kerbs); inside the board and on no piece. - `hazards?: TrafficHazard[]` — Moving obstacles, checked against each route step at the tick it would happen. - `maxMistakes?: number` — Blocked release attempts allowed before the level is lost, 0 to 100; 0 (the default) means no limit. ### `TrafficDifficulty` ```ts type TrafficDifficulty = 'easy' | 'medium' | 'hard' | 'very-hard' ``` Generator tier: a larger board and, from medium up, fewer open routes and longer chains of blockers. ### `TrafficEvent` ```ts type TrafficEvent = { type: 'released' | 'departed'; id: string; } | { type: 'tick'; tick: number; } | { type: 'mistake'; reason: string; } ``` What a move did: a piece was `released` or has `departed` (left the board), a `tick` passed, or a blocked release cost a `mistake`. ### `TrafficGenerateOptions` ```ts interface TrafficGenerateOptions ``` What `generateTrafficRelease` takes; everything but `seed` has a default. - `seed: number` — Unsigned 32-bit seed (0 included); the same options give the same level. - `difficulty?: TrafficDifficulty` — Tier; default `'medium'`. - `preset?: TrafficPreset` — What to build; default `'parking'`. - `layout?: TrafficLayout` — The shape filled; default `'rectangle'` (flat) or `'cube'` (voxels). - `size?: number` — Board side in cells: 2 to 12 flat (default 4, 6, 8, 10 by tier; parking adds a one-cell border) or 2 to 6 for voxels (default 2, 3, 4, 5). - `density?: number` — Share of the shape's places that get a piece, 0.35 to 1; default 1. - `hazards?: boolean` — Flat presets: add a pedestrian just off the left edge of row `floor(size / 2)`, there for 2 ticks in every 6, so a car leaving that way must wait for a gap; default false. - `maxMistakes?: number` — Blocked releases allowed before the level is lost, 0 to 100; default 0 (no limit). - `attempts?: number` — Candidate levels to try before throwing, 1 to 1,000; default 40. - `maxInitialChoices?: number` — Most pieces that may be clear at the start, 1 to 256; default by tier (streets 256, 5, 3, 3; voxels 256, 5, 3, 2, and 6 for a diamond; parking 256). - `minDependencyDepth?: number` — Least length of the longest chain of pieces blocking one another, 1 to 256; default by tier (1, 4, 7, 10; parking 1). ### `TrafficHazard` ```ts interface TrafficHazard ``` A moving obstacle (a pedestrian, a train) that repeats: at tick `t` it covers `phases[t % phases.length]`. - `id: string` — Unique non-empty id. - `phases: Voxel[][]` — 1 to 30 phases of cells it covers; an empty phase is a safe moment to cross. All hazards together repeat within 120 ticks. ### `TrafficLayout` ```ts type TrafficLayout = 'rectangle' | 'courtyard' | 'staggered' | 'cube' | 'pyramid' | 'arch' | 'diamond' ``` The shape filled: `rectangle`, `courtyard` (a hole in the middle) or `staggered` (a notched edge) for flat presets; `cube`, `pyramid`, `arch` or `diamond` for `voxels`. ### `TrafficLevel` ```ts interface TrafficLevel ``` A generated level: its configuration, a winning solution and what was measured. - `seed: number` — The seed asked for (the accepted candidate may have been drawn from a later one, but this seed reproduces it). - `difficulty: TrafficDifficulty` — The tier asked for. - `parameters: Required>` — The settings used, defaults filled in. - `config: TrafficConfig` — The level, ready for `createTrafficRelease`. - `solution: TrafficAction[]` — A replay-checked winning sequence of releases and ticks. - `metrics: { /** Pieces on the board. */ pieces: number; /** Pieces clear to leave at the start. */ initialChoices: number; /** Pieces with no clear route at the start. */ blockedPieces: number; /** Longest chain of pieces each blocking the next along the solution's routes. */ dependencyDepth: number; /** Solution routes that turn a corner (streets). */ turningRoutes: number; /** Whether the level met the targets below; always true for a returned level. */ difficultyTargetMet: boolean; /** The open-route target the level met. */ maxInitialChoices?: number; /** The chain-depth target the level met. */ minDependencyDepth?: number; }` — The level's structure; none of it claims a shortest plan or a human difficulty. ### `TrafficMotion` ```ts interface TrafficMotion ``` A piece on its way out. - `id: string` — The piece's id. - `route: string` — The route it took. - `frame: number` — Which of the route's footprints it is on now. - `reserved: Voxel[]` — Every cell its route sweeps, held until it is off the board, so nothing else may cross its path. ### `TrafficPiece` ```ts interface TrafficPiece ``` A car, block or voxel with the routes it can leave by. - `id: string` — Unique non-empty id. - `key?: string` — Optional colour or kind for the presenter (and for `boarding-queue`'s buses); the rules ignore it. - `cells: Voxel[]` — The cells it covers, 1 to 64, inside the board and on no other piece or wall. - `routes: TrafficRoute[]` — Its ways out, at least one. Releasing takes one of them whole. ### `TrafficPreset` ```ts type TrafficPreset = 'parking' | 'streets' | 'voxels' ``` What `generateTrafficRelease` builds: `streets` (Traffic Escape: cars on a road grid, some turning), `voxels` (Tap Away: a block of cubes, each leaving along one of six axes) or `parking` (a walled lot whose cars can leave either way along their axis; Bus Out's lot). ### `TrafficReleaseApi` ```ts type TrafficReleaseApi = typeof kit & { /** Same seeded generator off-thread; frame-delivered results require a started game. */ generateTrafficReleaseAsync(options?: kit.TrafficGenerateOptions, job?: { signal?: AbortSignal }): Promise; } ``` Public headless traffic release puzzles helpers. ### `TrafficRoute` ```ts interface TrafficRoute ``` One way out for a piece: its footprint at every step, from where it stands to wholly off the board. - `id: string` — Non-empty id, unique among the piece's routes; actions name it. - `frames: Voxel[][]` — 2 to 65 footprints. The first is the piece's `cells`; each next one keeps the same cells in the same order, each moved at most two steps (so a turn can pivot); the last lies wholly outside the board. ### `TrafficState` ```ts interface TrafficState ``` Where a traffic puzzle stands. - `remaining: string[]` — Ids of the pieces still on the board, moving ones included. - `moving: TrafficMotion[]` — The pieces on their way out. - `departed: string[]` — Ids of the pieces that have left, in order. - `tick: number` — Ticks played. - `moves: number` — Releases played. - `mistakes: number` — Blocked releases counted against `maxMistakes`. ### `Voxel` ```ts interface Voxel ``` A cell, in whole numbers from -64 to 64: `x` across, `y` the board's depth (rows on a flat board), `z` height (0 on a flat board). - `x: number` — Column across the board. - `y: number` — Row, or depth into a volume. - `z: number` — Layer up from the floor; 0 on a flat board. --- ## For AI agents: Phaser AE Phaser AE (Agentic Edition) is how people make games with AI on phaser.io. 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