---
title: "Shape-placing puzzles: API"
package: "@phaser-ae/placer"
tier: Pro
version: 3.0.0-3
released: 2026-10-14
updated: 2026-10-20
description: "Block-placing puzzle rules where a hand of fixed shapes is dropped onto a grid and full rows, columns and boxes clear, with a game-over test that never misses a move."
url: https://phaser.io/packs/placer/api
site: Phaser - https://phaser.io
---

# Shape-placing puzzles: API

`@phaser-ae/placer` — A hand of fixed shapes dropped onto a grid, clearing full rows, columns and boxes, as in games like 1010!, Block Blast and Woodoku.

## The pack

### `placer`

```ts
function placer(): Pack<{ placer: PlacerApi }>
```

The `placer` pack. Pure logic, so it needs no backend and runs headless.

## Helpers

### `createPlacer`

```ts
function createPlacer(cfg: PlacerConfig): Placer
```

Creates a `Placer` board from the given configuration. Throws when `cols` or `rows` is not an integer of at least
2, or when a region has a cell off the board.

### `PIECES_1010`

```ts
const PIECES_1010: PieceDef[]
```

The canonical 1010! piece set: lines 1–5, squares, L/T/S shapes.

### `PIECES_BLOCKS`

```ts
const PIECES_BLOCKS: PieceDef[]
```

Tetromino set (Block Blast leans on these), no rotation in tray games.

### `sudokuBoxes`

```ts
function sudokuBoxes(cols = 9, rows = 9, box = 3): RegionDef[]
```

The sudoku-box regions that tile a `cols` × `rows` board (default 9 × 9) with `box` × `box` squares (default 3),
left to right and top to bottom: Woodoku's nine 3×3 boxes of a 9×9 board by default, or `sudokuBoxes(8, 8, 4)`
for four 4×4 boxes of an 8×8. Ids are `box<bx><by>` by box column and row (`box00` at the top left), with a hyphen
between the two (`box10-3`) once a side has more than ten boxes. Throws when any argument is not a positive integer,
or `box` does not divide both `cols` and `rows`: a box that ran off the board could never fill.

## Classes

### `Placer`

```ts
class Placer
```

A drag-piece puzzle board (1010!/Woodoku style). Create one with `createPlacer`.

- `readonly cols: number` — The number of columns on the board.
- `readonly rows: number` — The number of rows on the board.
- `tray: Piece[]` — The pieces the player can place now. Refilled when empty.
- `score: number` — The score gained from placements and clears so far.
- `placements: number` — The number of pieces placed so far.
- `gameOver: boolean` — True when no tray piece fits on the board — the game is over.
- `streak: number` — Current clearing streak (consecutive placements that cleared ≥1 region).
- `constructor(cfg: PlacerConfig)`
- `cell(x: number, y: number): PlacedCell | null` — The placed cell at (x,y), or null.
- `canPlace(pieceId: number, at: XY): boolean` — Can `pieceId` be placed with its origin at `at`?
- `rotatePiece(pieceId: number, dir: 1 | -1 = 1): void` — Rotate a tray piece 90° in place (`dir` 1 = CW, -1 = CCW). No-op unless `rotate` is configured. Cells are re-normalised to a (0,0) origin.
- `place(pieceId: number, at: XY): PlaceResult` — Place a tray piece; commit, clear completed regions, refill when empty.
- `findPlacements(pieceId?: number): Placement[]` — Every legal placement of every tray piece (or one piece), scored, best first.
- `autoplay(maxPlacements = 500): PlaceResult[]` — Auto-play by a policy until game over; returns each result.
- `debugGrid(): string` — Rows of `#`/`.` — handy in tests.

## Types

### `Piece`

```ts
interface Piece
```

A live tray piece.

- `id: number` — The unique instance id of the piece.
- `cells: XY[]` — The cells of the piece, relative to its (0,0) origin.
- `tag?: string` — The label carried over from the piece definition, if it had one.

### `PieceDef`

```ts
interface PieceDef
```

A tray piece shape: cells relative to (0,0), plus a deal weight.

- `cells: XY[]` — The cells of the shape, relative to its (0,0) origin.
- `weight?: number` — Relative deal frequency. Default 1.
- `tag?: string` — Optional label carried onto placed cells and journal events.

### `PlacedCell`

```ts
interface PlacedCell
```

One placed board cell.

- `fill: number` — Piece-instance id that filled it (for colour/theming).
- `tag?: string` — The label carried over from the piece definition, if it had one.

### `Placement`

```ts
interface Placement
```

A legal placement found by `findPlacements`.

- `pieceId: number` — The id of the tray piece to place.
- `at: XY` — The board cell for the piece origin (its 0,0 cell).
- `clears: number` — Regions this placement would complete.
- `value: number` — Heuristic value, higher = better.

### `PlacerApi`

```ts
type PlacerApi = typeof kit
```

`game.placer` — every function and type this pack carries, as one namespace.

### `PlacerConfig`

```ts
interface PlacerConfig
```

Configures `createPlacer`. `cols` and `rows` must be integers of at least 2.

- `cols: number` — The number of columns on the board. Must be an integer of at least 2.
- `rows: number` — The number of rows on the board. Must be an integer of at least 2.
- `seed?: number` — The seed for the deterministic tray deals. Default 1.
- `regions?: RegionDef[]` — Extra clearable regions beyond the default rows+columns (e.g. sudoku boxes). Every cell must be on the board; the constructor throws on one that is not.
- `pieces?: PieceDef[]` — The deal pool. Default: the 1010! set.
- `traySize?: number` — Pieces per tray. Default 3.
- `rotate?: boolean` — Allow rotating tray pieces 90° (`board.rotatePiece`). Off in the classic games (1010!/Block Blast/Woodoku place pieces as dealt); opt in for a variant.
- `pieceFilter?: (fillRatio: number, pool: PieceDef[]) => PieceDef[]` — Adaptive/weighted piece generation hook (Block Blast style). Given board fill ratio 0..1, return the pool to draw from. Default: the static pool.
- `scorer?: (ev: { cellsPlaced: number; regions: number; streak: number }) => number` — Score a placement; called for every one, with `regions` 0 when nothing clears and `streak` the run before it. Default: the cells placed, plus a Block-Blast-like steep multi-region curve when it clears.

### `PlaceResult`

```ts
interface PlaceResult
```

The outcome of one `Placer.place` call.

- `valid: boolean` — True when the piece fit and was placed. False leaves the board unchanged.
- `steps: PlacerStep[]` — The ordered event journal for this placement — present the steps in order.
- `combo: number` — Regions cleared this placement (combo size).
- `streak: number` — Consecutive clearing placements including this one (0 if this cleared nothing).
- `gained: number` — The score gained by this placement.
- `gameOver: boolean` — True when no remaining tray piece fits on the board.

### `PlacerStep`

```ts
type PlacerStep = | { type: 'place'; pieceId: number; cells: XY[]; fill: number } | { type: 'regionClear'; regions: string[]; cells: XY[] } | { type: 'trayRefill'; pieces: { id: number; cells: XY[] }[] } | { type: 'gameOver' }
```

One event in a placement journal: a place, a region clear, a tray refill, or game over.

### `RegionDef`

```ts
interface RegionDef
```

A clearable region: a named set of cells that vanishes when all are filled.

- `id: string` — The unique name of the region, reported in `regionClear` steps.
- `cells: XY[]` — The cells that make up the region.

### `XY`

```ts
interface XY
```

A board cell position.

- `x: number` — The column of the cell.
- `y: number` — The row of the cell.

---

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