README.md

---
license: mit
pretty_name: OpenFront.io game-state snapshots
tags:
  - reinforcement-learning
  - games
---

# OpenFront.io game-state snapshots

250 bot/nation-only games of [OpenFront.io](https://openfront.io) (25 games on
each of 10 maps), played headless on the real deterministic game engine
([openfrontio/OpenFrontIO](https://github.com/openfrontio/OpenFrontIO)) and
snapshotted every 10 ticks / 1s of game time (~375k snapshots total).

Generated by and documented at
**[github.com/djmango/openfront-ai](https://github.com/djmango/openfront-ai)** —
see the repo for loaders, training code, and results.

**Format v3**: every snapshot captures the *complete* game state — the tile
grid plus all entities (players, diplomacy, units, attacks in flight) — so a
single snapshot is enough to reconstruct everything an agent could observe.
The 10-tick cadence means a typical nuke flight (20-60 ticks) spans 2-6
snapshots, and units in transit carry their destination.

One tar per map. Each game directory contains:

- `terrain.bin` — uint8[w*h] immutable terrain (bit 7 land, bit 6 shoreline,
  bit 5 ocean, bits 0-4 magnitude; magnitude 31 = impassable)
- `states/t<tick>.bin.gz` — gzipped little-endian uint16[w*h] mutable tile
  state: owner smallID in bits 0-11 (0 = unowned), fallout bit 13, defense
  bonus bit 14
- `states/t<tick>.json.gz` — gzipped JSON with full entity state:
  - `players`: id (smallID), name, type, troops, gold, tiles, alive, traitor,
    disconnected, targets, embargoes, pending alliance requests (in/out),
    sparse relation list
  - `alliances`: `[playerA, playerB, expiresAtTick]` for each active alliance
  - `units`: type (city, port, warship, transport, silo, SAM, nukes in
    flight, ...), owner, x, y, target tile tx/ty (null if idle — for nukes
    this is the impact point), samLock (a SAM is intercepting), level,
    health, constructing, cooldown, troops
  - `attacks`: from, to (0 = terra nullius), troops, retreating, srcX/srcY
    (boat-landing origin, null for land attacks)
- `meta.json` — format version, map, dims, snapshot tick list, winner

A game evolving (each color a player, Onion map, ticks 3175 and 12375):

![mid game](preview_mid.png) ![late game](preview_late.png)

Generated by [djmango/openfront-ai](https://github.com/djmango/openfront-ai)
for training observation encoders for RL agents.