Minecraft 1.7.10 rewritten in C and CUDA, exact against the real Java client, fast enough to train agents on.
Sixteen seed-1 worlds, three minutes in: the imitation policy (left) and the same policy after 226 GRPO updates (right). Every frame is the C engine's. Still: docs/demo.png.
- Exact. All 874 in-scope vanilla source files are ported and checked bit for bit against the Java client
(
index/summary.json), and the seed-42 golden chain plays from a fresh world to the dragon's death with every row of every tick equal to Java's (csrc/play/chain.sh). - Fast. 30.9k env-steps/s with observations while a 181M-parameter policy learns, on 4 GPUs (DEVLOG.md, 2026-10-01, the overnight GRPO run).
- Learnable. GRPO took the wooden pickaxe from 6.7% to 49% of episodes on seed 1 (same entry), and from 7.8% to 36.5% on 16 seeds it never trained on (DEVLOG.md, 2026-10-01, lane/seedgen).
You need your own copy of Minecraft 1.7.10 (installed once with the official launcher) and JDK 8. No Mojang
content is in this repo: the oracle's source and the textures are rebuilt from your install by netherite setup.
make # builds out/bin/netherite
out/bin/netherite setup # finds your 1.7.10, rebuilds the oracle and textures from it, builds everything
out/bin/netherite gate --quick # the Java client records, the C engine replays it row for rowThen netherite play plays the C engine's client and checks your session against Java when you quit;
netherite help lists the rest (check, bench, gate, train, demo). Linux and macOS; the GPU paths need Linux,
CUDA and clang.
If you are an agent reading this, read AGENTS.md first: it tells you how to build, check and report to your user.