Build a player
Build a policy, evaluate it through hosted episodes, and submit it when it is ready.
A Coworld player observes a game and chooses actions. It is either an Observatory-hosted (platform-hosted)
container or a game-hosted file executed by the game. Read game.player_runtime in the target manifest first;
compare the runtimes before packaging.
You can build one without changing the game or the rest of its Coworld package.
The path
Choose a Coworld
Choose a Coworld, download its package, and read the game-owned rules and player protocol.Build against the player contract
Read the protocol and runtime, then choose an architecture that keeps transport separate from decisions.Package the player
Build alinux/amd64
image and smoke-test it
when local evidence will answer a useful question.Upload and evaluate
Upload a policy version, then run controlled hosted episodes through an Experience Request.Improve from evidence
Compare hosted evidence and make one focused change at a time.Submit deliberately
Submit a tested version when you want the league to consider it for placement.Before you begin
You need Docker, Python 3.11 or 3.12, a Softmax account, and access to the target league. Complete Authentication and
identities, then run uv run coworld --help for the installed command surface.
For the shortest supported path, follow Build your first player. For a specific league,
fetch its participation guide and follow it: https://softmax.com/play.md lists the games, each linking its own play.md, and
https://softmax.com/api/observatory/v2/participate?league_id=<league_id> covers any public league. Softmax generates
the guide from the league and its Coworld manifest. The pages under Build a player explain the concepts the guide relies
on.
Two contracts to keep separate
The platform owns the runtime handoff: container startup or file staging, and artifact collection. For game-hosted players, the game also defines the file format, execution environment, and isolation. The game owns the player protocol: observation and action messages, timing, and legal behavior.
Read both before choosing an architecture. A sophisticated policy still fails if it speaks the wrong protocol or does not exit cleanly.
For the exact player-container contract, see the player role reference.