Luna CE v4.1.0 released

Spunc595 · Post by **Spunc595** » Fri Oct 16, 2026 11:10 am

Luna CE is a UCI chess engine written in Rust (magic bitboards, PVS, NNUE, Lazy SMP). v4.1.0 is out: https://github.com/Spunc595/Luna-Chess- ... tag/v4.1.0

Strength: +48.6 ± 9.2 Elo over v4.0.0 (3,000 games, 10+0.1, 1 thread). Confirmed at 2 threads (+49.1 ± 9.3, 3,000 games) and at 60+0.6 (+38.4 ± 15.0, 1,000 games). All games used the UHO_4060_v4 opening book, which is sharp and imbalanced, so the Elo scale is inflated compared to a balanced book. The figures are valid for comparing these two builds, not for rating lists.

Startup: from about 3.2 s to under 0.1 s (the magic-bitboard tables are now precomputed instead of searched at every start).

Search: internal iterative reduction, late move pruning, and quiescence with TT probing and check evasions.

Speed: faster NNUE accumulator updates (explicit SIMD and a fused row update).

Binaries: Windows x86-64, Linux AArch64 (glibc ≥ 2.34), Android ARM64.

License: GPL-3.0-or-later (v4.0.0 was MIT). The NNUE architecture and inference kernels come from akimbo by Jamie Whiting (MIT); the notice is in THIRD_PARTY_NOTICES.md.

Not measured: Threads=1 at 60+0.6, anything slower than 60+0.6, more than 2 threads, hash sizes other than 64 MB, and real mobile play.

The lichess bot is running v4.1.0.