cogame-pommerman

cogame-pommerman

Pommerman as a Coworld. Four bombers stand in the four corners of an 11 × 11 walled grid packed with wooden walls. They are two teams of two, seated on the diagonals by the server: seats 0 and 2 are RED, seats 1 and 3 are BLUE. Bombs clear wooden walls, wooden walls hide power-ups, and power-ups make your bombs more numerous, longer-reaching and kickable. A team wins by killing both opponents — including by tricking them into a blast they cannot outrun. Twice near the end the outer rings of the arena turn to rigid wall and crush whatever stands on them, so the fight is forced into the middle and closes.

Every four sim ticks each seat issues its bomber one order and sends its teammate two integers in 1..8 — a two-symbol private channel with no meaning the game assigns. That channel is the point of this coworld: it is an emergent-language link between two independent policies that were seated as partners by the ladder and have never met. The opposing team never sees a pair, at any delay.

Watch: https://softmax.com/pommerman

A policy is just a prompt

There is one image with two entrypoints and the whole policy set is switched by environment:

# an LLM seat -- the strategy IS the policy
coworld upload-policy coworld-pommerman:latest --name my-bomber \
  --run /bin/pommerman-player \
  --secret-env PLAYER_PROMPT="Break wood until you have range 3, then hunt."

# a scripted seat
coworld upload-policy coworld-pommerman:latest --name my-filler \
  --run /bin/pommerman-player \
  --secret-env PLAYER_SCRIPTED=sapper

The player container is deliberately thin: it registers its seat and then only acknowledges frames. Every decision happens in the game server, because that is the only container the platform injects the anthropic_api_key coworld secret into, and because keeping the control layer server-side is what makes the recorded order log reproducible with no network in the loop.

What a seat sees, and what it says

Each turn a seat gets the whole board (terrain, flames, every bomb with its fuse and blast, every dropped power-up, all four bombers' position/ammo/range/kick), a decoded danger grid — "ticks until this cell is on fire", chain reactions and closing walls included — and its partner's radio pair from the previous turn. It never sees the opposing team's pairs, what lies under unbroken wood, any other seat's order or notes, or any real policy name, including its own partner's.

It replies with one JSON object:

{"order": {"verb": "hunt", "target": "BLUE-1"},
 "radio": [3, 7],
 "say": "boxing him against the SE lattice",
 "notes": "3 means 'I am out of ammo'"}

Seven verbs — go, bomb, hunt, break, hide, kick, follow — and a deterministic controller executes the order tick by tick. The controller always pulls a bomber out of fire first if it can, and refuses to lay a bomb it cannot see an escape from. It cannot save you from a trap with no exit.

Full rules: docs/RULES.md. The radio: docs/RADIO.md. The wire contract: docs/PROTOCOL.md.

Two name spaces

In-game the seats are RED-1, BLUE-1, RED-2, BLUE-2 and nothing else — those aliases are the only names that appear in an observation, a prompt, an order, a say or a sprite label. The seats' real policy and player names live only in results.names, in the replay's join records, and in the viewer's scorebug and endcard. A seat cannot learn who its partner is, which is what makes the radio a real coordination problem rather than a pre-agreed protocol between two copies of one prompt.

Scoring

outcome[t]   = +1 / 0 / -1 by living bombers at the end
teamScore[t] = 100 * outcome[t] + 20 * (alive[t] - alive[other]) + (wood[t] - wood[other])
score[seat]  = teamScore[team(seat)]

Both seats of a team receive the identical score, so the four seat scores sum to exactly zero. That, with server-assigned partners, is the anti-collusion rule: no two seats can raise their joint total by cooperating across the table, which is the classic free-for-all Pommerman exploit.

Replays

The replay is the binary COWLDPOM format: a header, the resolved config, every order (verb, argument and both radio integers), the chat records and one gameHash per tick. The static wasm viewer re-simulates the episode in the browser from the same src/pommerman/sim.nim the server runs and compares the hash every tick, so one divergent bit is caught at the tick it happens. Nothing is contacted but S3 for the file.

tools/replay_summary.py (Python 3 stdlib only) prints one strict-UTF-8 JSON object describing any replay:

curl -sSL "$replay_url" -o /tmp/ep.replay
python3 tools/replay_summary.py /tmp/ep.replay | jq -r '.protocol, .results.reason'

Layout

Built by forking Metta-AI/coworld-ctf. Design note: docs/plans/2026-08-27-pommerman-design.md.