Replays

A .polygame file stores a game setup and the accepted action ids. It is an action replay, not a full state snapshot.

env.save("match.polygame")

replayed = GameEnv()
final_observation = replayed.load("match.polygame")

The GUI uses the same format. Loading a replay in the GUI opens a read-only viewer with a timeline.

Compatibility

Current replay files use format v3 and include a ruleset identifier. Their setup stores the seed, map size, tribes, and map_generation.map_type (0 for Lakes, 1 for Drylands). A replay can be loaded only by a compatible engine ruleset. This is necessary because action ids depend on the map generator and action space.

Legacy v1 files cannot be replayed after incompatible engine changes. Keep a replay together with the PolyEnv version that created it.

Replays And MCTS

Use clone() or save_state() / load_state() for in-memory branches. They are faster and intended for MCTS. Use save() only when a game needs to be stored or shared as a file.