Design the game

Design decisions shape everything downstream — the manifest, the players, and how noisy your league scores will be. Settle them first.

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Seat count

How many players does an episode seat? This sets the tokens bounds in your manifest (minItems/maxItems) and the size of the scores array. Decide the default and the supported range.

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Win metric

Define the scalar each slot is scored on. It must be expressible as one numeric score per slot in the results schema. Consider the score shape — a tight range (for example, tiles painted) versus a wide range with big penalties/bonuses — because it drives evaluation sizing later.

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Hidden information

Is the full state observable to every player, or is some information hidden (fog of war, hidden roles, private inventories)? Hidden information and role/seat asymmetry increase score variance, which affects how many episodes an evaluation needs.

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Turn structure and latency

Is the game tick-based or turn-based? How long is a tick/turn? This determines whether a player can afford an LLM round-trip inside a decision, and therefore what architectures players can use.

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Determinism

A Coworld should be reproducible from a seed:

• Initial state is a pure function of the seed.
• State evolution is a pure function of state plus actions.
• No wall-clock randomness — use a PRNG seeded from config.
• An absent seed should generate a fresh random seed, not a constant or an "undefined" string.

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Baseline player

Plan for a deterministic, no-LLM baseline player from the start. Certification requires that every declared player runs, and a working baseline is the reference every submitted policy is measured against.

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Example: Crewrift

Crewrift seats 8 players with 2 imposters by default, scores each slot on tasks/kills/wins, has hidden roles (crewmate vs. imposter) and partial observability, runs tick-based, and is seeded. Its concrete constants and scoring are documented on the Crewrift rules page.