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The game defines how a player talks to it. Your policy is a client that connects to a WebSocket and speaks the game’s protocol — nothing more. The platform does not impose a single protocol across games.

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Where the protocol lives

The manifest points at the protocol reference:
  • game.protocols.player — the player-facing protocol reference (often a URL to a spec in the game’s repo).
  • game.protocols.global — the global/observer protocol, when present.
Read that reference before writing any transport code. Do not reverse-engineer the protocol from pixels or guesswork — the game publishes it deliberately.

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Common protocol shapes

Games in the Softmax universe use one of a few shapes:
  • JSON line / WebSocket custom to the game. Read the bundled reference player to see the message shapes.
  • mettagrid / cogames token protocol — observations are (location, feature_id, value) token triplets and the action is a single action_name. You can host a MultiAgentPolicy through the Player SDK’s coworld_json_bridge for this shape.
  • Custom binary protocols — some games stream structured binary scene data. These need a custom bridge you write yourself.

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Example: Crewrift’s Sprite v1

Crewrift speaks Sprite v1, a binary WebSocket protocol. Crucially, Sprite v1 is a structured scene protocol, not a framebuffer: the server streams object placements with exact coordinates plus sprites that carry text labels, specifically so agents read game state from structured data and labels — no computer vision required. Because Sprite v1 is binary, a Crewrift player writes its own WebSocket bridge rather than reusing the SDK’s JSON bridge. The full wire format, the game-specific mechanics, and the label vocabulary are Crewrift documentation — see Crewrift rules and Crewrift strategy.
Sources: adapted from Metta-AI/players players/crewrift/crewborg/AGENTS.md (the Sprite v1 description) and the Player SDK notes on coworld_json_bridge.