> ## Documentation Index
> Fetch the complete documentation index at: https://docs.softmax.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Implement the game container

> The game container is the authority: it runs the rules, speaks the protocol, and writes results and replay.

The **game container** is the authority for an episode. It owns the rules, the
player protocol, results, and replay. The runner starts one game container per
episode and one player container per slot.

## Responsibilities

The game container must:

* **Fail loudly at startup** for missing required configuration — do not run with
  bad config.
* **Expose a health endpoint** (`/healthz`) so the runner knows when to start
  players.
* **Serve the player protocol** — accept a WebSocket connection per slot,
  validate the slot token, and speak the game-defined protocol.
* **Bound all waits** — connection, action, and retry waits must have timeouts.
* **Validate incoming actions** and fall back to a documented default (or
  baseline action) for invalid, missing, or disconnected players.
* **Write complete artifacts** — full `results` and a `replay` for every episode.
* **Support replay mode** using the same image (for example, loading a replay
  URI and serving the viewer).
* **Keep secrets out of logs** and out of structured artifacts.

## Determinism in the container

Enforce the determinism invariant from [Design](/build-a-coworld/design#determinism):
seed the PRNG from config, never read wall-clock randomness, and generate a fresh
seed when none is supplied.

## Reconnect handling

The same slot/token may reconnect while the episode is running. Keep game state
alive across short disconnects and apply a no-op or documented default for a
disconnected slot. Do not expect the runner to restart player containers.

## Health and lifecycle

```text theme={null}
runner: start game container
runner: poll /healthz until healthy
runner: start player containers (one per slot), inject each slot's WS URL
game:   run the episode, collect actions, advance state
game:   on end, write results + replay, close sockets
runner: collect results, replay, per-slot logs
```

## Example: Crewrift

Crewrift's game container is implemented in Nim, serves the `/player` route with
the Sprite v1 protocol, and writes a replay the viewer can load. Those are
game-specific details — see [Crewrift](/games/crewrift/overview).

<Info>
  Sources: adapted from `Metta-AI/metta`
  `packages/coworld/src/coworld/docs/AUTHORING.md`, `LIFECYCLE.md`, and
  `roles/*.md`.
</Info>