---
title: "Excavation: API"
package: "@phaser-ae/excavation"
tier: Pro
version: 3.0.0-3
released: 2026-10-14
updated: 2026-10-19
description: "Diggable terrain for real-time digging games: bodies tunnel through earth, others follow the tunnels or ghost through the dirt, and rocks fall when undermined."
url: https://phaser.io/packs/excavation/api
site: Phaser - https://phaser.io
---

# Excavation: API

`@phaser-ae/excavation` — Diggable terrain: bodies tunnel through earth, follow tunnels or ghost through it; rocks and apples fall when undermined; collectibles in the dirt.

## The pack

### `excavation`

```ts
function excavation(): Pack<{ excavation: ExcavationApi }>
```

Install the renderer-independent excavation API: diggable terrain, tunnelling bodies, falling objects.

## Helpers

### `createExcavation`

```ts
function createExcavation(config: ExcavationConfig): Excavation
```

Build a diggable-terrain field. Throws a readable error for an unsupported configuration.

### `EXCAVATION_LEGEND`

```ts
const EXCAVATION_LEGEND: Readonly<Record<string, Terrain>>
```

The default map legend.

## Classes

### `Excavation`

```ts
class Excavation
```

A field of diggable terrain. Create one with `createExcavation`. Fixed-step and deterministic: the same
config, the same inputs and the same `step` sequence produce the same state, and `snapshot`/`restore`
round-trip it exactly.

- `readonly cols: number` — Columns of cells.
- `readonly rows: number` — Rows of cells.
- `readonly subdivisions: number` — Sub-cells per cell edge.
- `readonly tunnelWidth: number` — Default carve width as a fraction of a cell.
- `readonly strata: readonly number[]` — Start rows of the strata, ascending.
- `readonly collectRadius: number` — Pickup radius in cells.
- `constructor(config: ExcavationConfig)`
- `inBounds(x: number, y: number): boolean` — Whether a cell lies inside the field.
- `terrainAt(x: number, y: number): Terrain | null` — The authored terrain of a cell (what it was built as; whether it is dug now is `isOpen`/`dugFraction`).
- `isBedrock(x: number, y: number): boolean` — Bedrock or outside the field: nothing can dig it.
- `stratum(row: number): number` — Index of the stratum (layer of earth) a row belongs to; -1 above the first stratum.
- `subcellDug(gx: number, gy: number): boolean` — Whether sub-cell (gx, gy) is dug. Sub-cells are numbered from the field's top-left, `subdivisions` per cell.
- `isDugAt(x: number, y: number): boolean` — Whether the point (x, y) in cell units lies in dug space. Outside the field is never dug.
- `dugFraction(x: number, y: number): number` — Fraction of a cell's sub-cells that are dug (0..1).
- `isOpen(x: number, y: number): boolean` — Whether a cell's centre is dug through: a body can stand in it and an object can fall into it.
- `connected(a: Cell, b: Cell): boolean` — Whether two orthogonally adjacent cells are joined by dug earth along the line between their centres.
- `openings(x: number, y: number): Direction[]` — Directions with a dug connection out of an open cell (ignores objects and bodies).
- `region(x: number, y: number): number` — Connectivity region of an open cell: two cells share a region when a body could walk between them along dug connections. -1 for a cell that is not open. Recomputed lazily after digging.
- `distances(target: Cell): Int32Array` — Tunnel distance in cells from every cell to `target` along dug connections (-1 where unreachable or not open). Cached until the terrain changes.
- `tunnelDistance(from: Cell, to: Cell): number` — Tunnel distance between two cells, or -1 when one cannot walk from `from` to `to`.
- `route(from: Cell, to: Cell): Direction | null` — The first step along the shortest dug route from `from` to `to`, or null when there is none.
- `nearestOpen(p: Cell, maxRadius = Math.max(this.cols, this.rows)): Cell | null` — The nearest open cell to a point (by grid distance, ties in scan order), or null when nothing is dug.
- `carve(x0: number, y0: number, x1: number, y1: number): number` — Dig every sub-cell whose centre lies in the rectangle [x0, x1] x [y0, y1] (cell units), except in bedrock. Returns how many sub-cells were newly dug.
- `digCell(x: number, y: number): number` — Dig a whole cell (every sub-cell). Returns how many sub-cells were newly dug.
- `digTunnel(from: Cell, to: Cell, width = this.tunnelWidth): number` — Dig a straight tunnel between two cell centres with a given width (default `tunnelWidth`).
- `fill(x0: number, y0: number, x1: number, y1: number): number` — Refill the rectangle with earth (a hole closing up). Bedrock and sky cells are left alone. Returns sub-cells filled.
- `takeChanges(): Cell[]` — Cells whose dug sub-cells changed since the last call (for a renderer redrawing only what changed).
- `addBody(spec: BodySpec): BodyState` — Add a body. Digging bodies dig out the cell they start in.
- `removeBody(id: string): void` — Remove a body (it died, escaped or left).
- `body(id: string): BodyState | undefined` — A copy of one body's state, or undefined.
- `get bodies(): BodyState[]` — Copies of every body, in update order.
- `steer(id: string, direction: Direction | null): void` — Steer a held body: a direction moves it (cornering when the turn opens), null stops it.
- `want(id: string, direction: Direction): void` — Ask an auto body to take a direction at its next opportunity (overrides one decision).
- `setSpeed(id: string, speed: number): void` — Change speed (cells per second).
- `setFrozen(id: string, frozen: boolean): void` — Freeze or release a body (a frozen body does not move).
- `setBlocking(id: string, blocking: boolean): void` — Make a body block (or stop blocking) other grid bodies.
- `setFlags(id: string, flags: { collects?: boolean; pushes?: boolean; crushable?: boolean; control?: "held" | "auto"; digFactor?: number }): void` — Set the remaining behaviour flags of a body.
- `setMode(id: string, mode: BodyState["mode"], ghost?: { target: Cell; policy?: GhostPolicy }): void` — Change how a body moves. Entering `ghost` needs a target (updated later with `ghostTarget`); it lands by itself under `policy` and becomes `tunnel` again. Leaving ghost mode directly snaps it to its nearest cell.
- `ghostTarget(id: string, target: Cell): void` — Move a ghost's target (a ghost chasing a moving player).
- `place(id: string, at: Cell, direction?: Direction): void` — Put a body on a cell centre (a respawn): clears ghost, caught, crushed, frozen and steering.
- `exits(id: string): Direction[]` — Directions a body could move from its nearest cell right now: dug connections for tunnel bodies, any diggable neighbour for diggers, never into bedrock, objects it cannot push or blocking bodies.
- `addObject(spec: { id: string; kind: string; at: Cell }, ids = new Set(this.objectList.map((o) => o.id))): ObjectState` — Add a loose object at runtime (an apple a monster turned into).
- `removeObject(id: string): void` — Remove a loose object (eaten by a monster).
- `get objects(): ObjectState[]` — Copies of every loose object (gone ones are removed).
- `addItem(spec: { id: string; kind: string; at: Cell; group?: string }, ids = new Set(this.itemList.map((i) => i.id))): ItemState` — Add a collectible at runtime (a bonus vegetable).
- `removeItem(id: string): void` — Remove a collectible without collecting it (a bonus timing out, a monster eating it).
- `get items(): ItemState[]` — Copies of the collectibles still in the field.
- `objectIn(x: number, y: number): ObjectState | undefined` — The object resting (or wobbling, or crumbling) in a cell; falling objects are not in a cell.
- `step(dt: number, options: StepOptions = {}): void` — Advance the field by `dt` seconds: bodies (in order), pushes, pickups, then loose objects.
- `get time(): number` — Simulated seconds.
- `drain(): ExcavationEvent[]` — Take the events since the last drain.
- `snapshot(): ExcavationSnapshot` — A complete serializable copy of the field's mutable state.
- `restore(snap: ExcavationSnapshot): void` — Restore a snapshot taken from a field built from the same config.

## Types

### `BodyControl`

```ts
type BodyControl = "held" | "auto"
```

Who drives a grid body. `held`: it moves only while steered (a player's held stick) and corners when the
wanted turn opens. `auto`: it always moves at its speed and chooses a direction at every cell centre (the
`decide` hook of `step`, or a seeded wander).

### `BodyMode`

```ts
type BodyMode = "dig" | "tunnel" | "ghost" | "fixed"
```

How a body moves. `dig`: on the grid, carving earth as it goes (only bedrock, objects and blocking bodies stop
it). `tunnel`: on the grid, only along dug connections between cells. `ghost`: freely through anything,
towards a target, until it lands in an open cell (then it becomes `tunnel` again). `fixed`: does not move.

### `BodySpec`

```ts
interface BodySpec
```

A body to add to the field.

- `id: string` — Unique id.
- `kind?: string` — Free-form kind for the game ("player", "pooka" ...). Default "body".
- `at: Cell` — Start cell (its centre).
- `direction?: Direction` — Initial heading. Default "left".
- `mode?: BodyMode` — Movement mode. Default "tunnel".
- `control?: BodyControl` — Steering. Default "auto".
- `speed: number` — Speed in cells per second.
- `digFactor?: number` — Speed multiplier while carving fresh earth (dig mode). Default 1.
- `carveWidth?: number` — Width of the tunnel it carves, as a fraction of a cell. Default: the field's `tunnelWidth`.
- `turnBefore?: number` — Cornering window before a cell centre, in cells (0 <= w < 0.5): a perpendicular turn wanted this far short of a turn line is taken at once, sliding onto the line. Default 0 (turns only exactly on a centre, as the arcade enemies do). A player usually wants about 0.4 so a turn pressed a little early is never deferred.
- `turnAfter?: number` — Cornering window after a cell centre, in cells (0 <= w < 0.5): a turn wanted just past a line is taken there, sliding back onto it, rather than a whole cell later. Default 0.
- `collects?: boolean` — Picks up collectibles it passes. Default false.
- `pushes?: boolean` — Pushes pushable objects along tunnels when walking into them sideways. Default false.
- `crushable?: boolean` — Can be caught and crushed by falling objects. Default true.
- `blocking?: boolean` — Blocks other grid bodies from entering its cell. Default false.

### `BodyState`

```ts
interface BodyState
```

Serializable state of one body.

- `id: string` — Unique id.
- `kind: string` — Free-form kind.
- `mode: BodyMode` — Movement mode.
- `control: BodyControl` — Steering.
- `x: number` — Position in cell units (centre).
- `y: number` — Position in cell units (centre).
- `direction: Direction` — Heading (the last grid direction it moved or wants).
- `moving: boolean` — Whether it moved during the last step.
- `speed: number` — Speed in cells per second.
- `digFactor: number` — Speed multiplier while carving fresh earth.
- `carveWidth: number` — Carve width as a fraction of a cell.
- `turnBefore: number` — Cornering window before a centre, in cells.
- `turnAfter: number` — Cornering window after a centre, in cells.
- `steer: Direction | null` — The held direction (held control) or null.
- `frozen: boolean` — Frozen bodies do not move (stunned, inflated, caught).
- `blocking: boolean` — Blocks other grid bodies.
- `collects: boolean` — Collects items.
- `pushes: boolean` — Pushes objects.
- `crushable: boolean` — Can be crushed.
- `digging: boolean` — Whether it carved fresh earth during the last step.
- `caughtBy: string | null` — Id of the falling object carrying it, or null.
- `crushed: boolean` — Set once an object has landed on it.
- `ghost: GhostState | null` — Ghost state while in ghost mode.
- `walker: GridWalkerState` — The grid walker's state (grid modes).

### `Cell`

```ts
interface Cell
```

A cell, or a point in cell units.

- `x: number` — Column (or x in cell units).
- `y: number` — Row (or y in cell units), 0 at the top.

### `DecideContext`

```ts
interface DecideContext
```

Context passed to a `decide` hook at a cell centre.

- `body: BodyState` — The body deciding (a copy).
- `at: Cell` — The cell it is centred on.
- `exits: Direction[]` — Directions it can move from here (for tunnel bodies: dug connections; for diggers: any non-blocked cell).

### `Direction`

```ts
type Direction = "up" | "left" | "down" | "right"
```

One of the four grid directions.

### `ExcavationApi`

```ts
type ExcavationApi = typeof api
```

`game.excavation`: the diggable-terrain field (`createExcavation`), its legend and types.

### `ExcavationConfig`

```ts
interface ExcavationConfig
```

Everything a field is built from.

- `map: string[]` — The terrain, one string per row, all the same length. Default legend: `#` earth, space or `.` tunnel, `~` sky, `=` bedrock. Any number of columns and rows (up to the documented cell budget).
- `legend?: Record<string, Terrain>` — Extra or replacement map characters.
- `subdivisions?: number` — Sub-cells per cell edge (2..16). Default 4. Higher is a finer dig.
- `tunnelWidth?: number` — Width a digging body carves, as a fraction of a cell (0 < w <= 1). Below 1, parallel tunnels keep a wall between them. Default 0.75.
- `strata?: number[]` — Start row of each stratum (layer of earth), ascending. Default: one stratum from row 0.
- `tunnels?: TunnelSpec[]` — Straight tunnels carved at start (as a body would dig them).
- `objectKinds?: Record<string, LooseObjectKind>` — Loose object kinds.
- `objects?: ObjectSpec[]` — Loose objects.
- `items?: ItemSpec[]` — Collectibles.
- `collectRadius?: number` — Radius in cells within which a collecting body picks an item up. Default 0.45.
- `seed?: number` — Seed for the default wander policy. Default 1.

### `ExcavationEvent`

```ts
type ExcavationEvent = | { kind: "dig"; id: string; cell: Cell; subcells: number; distance: number } | { kind: "collect"; item: string; itemKind: string; group: string; by: string; at: Cell } | { kind: "loosen"; object: string; at: Cell } | { kind: "fall"; object: string; at: Cell } | { kind: "catch"; object: string; body: string } | { kind: "land"; object: string; at: Cell; fell: number; broken: boolean; caught: string[] } | { kind: "remove"; object: string } | { kind: "push"; object: string; by: string } | { kind: "ghost"; id: string } | { kind: "materialise"; id: string; at: Cell }
```

Something that happened during a step. Drain them with `drain()`.

### `ExcavationSnapshot`

```ts
interface ExcavationSnapshot
```

A complete serializable snapshot of a field.

- `dug: string` — Dug sub-cells, packed bits as hex.
- `bodies: BodyState[]` — Bodies in update order.
- `objects: ObjectState[]` — Loose objects.
- `items: ItemState[]` — Collectibles still in the field.
- `random: RngState` — The wander stream: the kernel generator's state (four words, from `rng.snapshot()`), so a restore repeats the draws.
- `time: number` — Simulated seconds.

### `GhostPolicy`

```ts
interface GhostPolicy
```

Where a ghost may land.

- `minSeconds?: number` — Minimum seconds as a ghost before it may land. Default 0.5.
- `maxSeconds?: number` — After this many seconds any open cell will do. Default: never relax.
- `landing?: "any" | "other-region" | "target-region"` — `any`: any open cell. `other-region`: an open cell not connected to the tunnel it left. `target-region`: an open cell connected to the target's cell. Default `other-region`.
- `row?: number` — Only land on this row (an escape to the surface).
- `keepAway?: number` — Never land within this many cells of the target (eyes do not reappear on top of the player). Default 0.

### `GhostState`

```ts
interface GhostState
```

Ghost state of a body in `ghost` mode.

- `target: Cell` — The point it floats towards.
- `elapsed: number` — Seconds spent as a ghost.
- `policy: GhostPolicy` — The landing policy.
- `origin: number` — Connectivity region of the tunnel it left (-1 when it left from earth).
- `landing: Cell | null` — The open cell it is settling into, once chosen.

### `ItemSpec`

```ts
interface ItemSpec
```

A collectible embedded in the earth (or lying in a tunnel).

- `id: string` — Unique id.
- `kind: string` — Free-form kind ("cherry", "gold", "vegetable").
- `at: Cell` — Cell it sits in.
- `group?: string` — Optional group id (a Mr. Do! cherry cluster).

### `ItemState`

```ts
interface ItemState
```

Serializable state of one collectible.

- `id: string` — Unique id.
- `kind: string` — Free-form kind.
- `x: number` — Cell it sits in.
- `y: number` — Cell it sits in.
- `group: string` — Group id or "".

### `LooseObjectKind`

```ts
interface LooseObjectKind
```

Behaviour of one kind of loose object (a rock, an apple, a boulder).

- `wobbleSeconds?: number` — Seconds it wobbles after losing support before it falls. Default 0.5.
- `fallSpeed?: number` — Fall speed in cells per second. Default 6.
- `heldBy?: string[]` — Body kinds that hold it up: while one of them stands directly beneath it (the digger who undermined it), it does not start to wobble. Default none.
- `breakAfter?: number` — Cells fallen at which landing breaks it. 0 always breaks (a Dig Dug rock crumbles wherever it lands); 2 breaks after falling more than its own height (a Mr. Do! apple); a negative value never breaks. Default 0.
- `crumbleSeconds?: number` — Seconds a broken object stays (crumbling) before it is removed. Default 0.6.
- `pushable?: boolean` — Bodies that push can shove it sideways along tunnels. Default false.
- `catchWidth?: number` — Half-width of the catch zone in cells: bodies whose centre is closer than this horizontally are caught. Default 0.6.

### `ObjectPhase`

```ts
type ObjectPhase = "rest" | "loose" | "falling" | "landed" | "gone"
```

Lifecycle of a loose object.

### `ObjectSpec`

```ts
interface ObjectSpec
```

A loose object to place.

- `id: string` — Unique id.
- `kind: string` — Kind key into `objectKinds`.
- `at: Cell` — Cell it rests in.

### `ObjectState`

```ts
interface ObjectState
```

Serializable state of one loose object.

- `id: string` — Unique id.
- `kind: string` — Kind key.
- `x: number` — Centre in cell units.
- `y: number` — Centre in cell units.
- `phase: ObjectPhase` — Lifecycle.
- `timer: number` — Seconds left in the current phase (wobble or crumble).
- `fromY: number` — The y where the current fall began.
- `fell: number` — Cells fallen in the last fall.
- `caught: string[]` — Bodies caught by the current fall.
- `broken: boolean` — Whether it broke on landing.
- `pushedBy: string | null` — Id of the body pushing it during the last step, or null.

### `StepOptions`

```ts
interface StepOptions
```

Options for one step.

- `decide?: (ctx: DecideContext) => Direction | null` — Chooses the heading of an `auto` body at each cell centre. Return a direction from `exits`, or null to let the field's seeded wander choose. Called in body order; deterministic if the hook is.

### `Terrain`

```ts
type Terrain = "earth" | "tunnel" | "sky" | "bedrock"
```

What a map character means. `earth` is diggable and starts solid. `tunnel` starts dug the way a body digs
(walls left between parallel tunnels) and joins every orthogonal `tunnel`/`sky` neighbour. `sky` starts
completely clear (a surface row). `bedrock` is solid and can never be dug.

### `TunnelSpec`

```ts
interface TunnelSpec
```

A pre-dug straight tunnel between two cells in the same row or column.

- `from: Cell` — One end.
- `to: Cell` — The other end.

---

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