Pluto

Pluto is a StarCraft: Brood War AI. A single neural network, trained by self-play reinforcement learning, plays the whole game — macro and micro, all three races; there is no scripted play. It plays 1v1 melee through BWAPI (https://bwapi.github.io/).

Status: binary releases. This repo hosts binary releases of Pluto. The current one is the model that played the CoG 2026 StarCraft AI Competition (md07x02_cog2026_2578600_int8mv), with CPU inference — no GPU needed. Grab it from the Releases page.

Requirements

• StarCraft: Brood War 1.16.1 + BWAPI 4.4.0
• 64-bit Windows, or Wine (StarCraft is 32-bit; the inference engine is a separate 64-bit process)
• An x86-64 CPU with AVX2 (Intel Haswell 2013+ / any AMD Zen). AVX-VNNI (Intel 12th gen 2021+ / AMD Zen 5) roughly doubles inference speed and is strongly recommended.
• 6+ cores recommended; ~2 GB free RAM, ~0.4 GB disk space

Install

Unpack the release zip into your StarCraft folder's bwapi-data/AI/ (the usual place for bots), so the files land like this:

bwapi-data/AI/pluto.dll                 32-bit BWAPI module
bwapi-data/AI/pluto/pluto_infer.exe     64-bit CPU inference engine
bwapi-data/AI/pluto/pluto_weights.bin   network weights (int8)

Point bwapi.ini at the DLL as usual: ai = bwapi-data/AI/pluto.dll

Register the bot as Zerg, Terran, Protoss, or Random — it plays all of them. It announces itself in chat on game start: "Pluto online (md07x02_cog2026_2578600_int8mv). gl hf!"

The binaries are unsigned, so Windows SmartScreen or antivirus software may warn on first run.

How it runs

On game start, pluto.dll launches pluto_infer.exe (found next to the DLL) and talks to it over shared memory. No network connections are made and no files outside the StarCraft folder are touched. The engine process exits with the game.

The model takes one step every 6 game frames. The DLL gives the engine up to 40 ms in the frame it observed and, if the answer isn't in by then, waits for it at the next frame — so every decision is acted on exactly when the model was trained to expect it. On a slow CPU the game runs slower; the bot does not play worse. A step takes ~20 ms on a current desktop CPU and ~60 ms on a 2021 6-core (i5-12500T) with 200 units on the map, up to ~3x that in big late-game fights. When the stalls stay long for a sustained stretch, Pluto says so once in chat ("Pluto: this machine can't keep up ... sorry about the pace") and notes it in its game record.

If the engine cannot start (missing files, unsupported CPU) or dies mid-game, the bot reports the reason in game chat and in the logs ("Pluto: quitting in 10 seconds"), then exits the StarCraft process. This looks like a crash, and is meant to: it is an error, not a game. Check pluto.log and pluto_infer.log in the StarCraft folder.

Files written

pluto.log          DLL log     (StarCraft folder)
pluto_infer.log    engine log  (StarCraft folder)
bwapi-data/write/pluto_bandit_<opponent>.txt
                   per-opponent build-order stats and the running
                   record against that opponent

The bot picks its opening with a bandit over the per-opponent win/loss counts; every build is listed with its mask and name, so you can edit the numbers to steer it. The file is re-read every game (from write/ or read/, whichever is newer, so the usual write/ -> read/ copy between games works too); if you edit it, bump the seq line so your copy wins and keep the closing end line. Below the stats, the file keeps one JSON line per game: a start record (opponent, map, chosen build), an end record (result, frame timing, the model's win-probability trajectory) and any error or resign events.

Notes

• The bot uncaps game speed and paces itself by inference (one model step every 6 frames, ~20-60 ms per step on the hardware above).
• Optional: run pluto_infer.exe --bench once per machine (~2-4 min). It times the thread counts on that hardware and writes the best one to pluto/pluto_config.json, which the engine then uses. Without it the engine uses up to 6 threads.
• BWRL_DRAW=1 in the environment draws the model's win-probability graph on screen (off by default; nice for watching games).
• Pluto resigns: when its own win estimate stays pinned at a loss for ~10 seconds it says "gg" and leaves the game. A mid-game engine failure exits the StarCraft process instead — it counts as a crash, deliberately, rather than as a loss.
• Two games against the same opponent must not run in parallel on one install (they share the stats file above; tournament managers already avoid this). Different opponents in parallel are fine.
• Under a tournament manager with a per-frame time limit (the usual 55 ms rule): the 40 ms budget is chosen for it — a step that finishes within the budget plus one frame period costs no frame more than the period, and only the overflow lands in one longer frame at the next step. On hardware where that still draws timeouts, set BWRL_STRADDLE=1: the DLL then never holds a frame past the budget, and a late decision slips to a later frame instead (the competition behaviour; the bot decides less often). BWRL_FRAME_BUDGET_MS=<ms> changes the budget for either mode.