NARC Next 4.1

Original C++20 UCI chess engine. Windows x86-64, statically linked, no DLLs
and no external network file required — the NNUE is embedded in the binary.

Which build to use

File	Requires	Notes
NARC-Next-4.1-x86-64-v3.exe	AVX2 / BMI2 (Haswell 2013+)	Recommended. ~25% faster.
NARC-Next-4.1-x86-64-v2.exe	SSE4.2 / POPCNT	Compatibility build for older CPUs.

Both are functionally identical and produce identical node counts at a fixed
depth; they differ only in speed. Neither is built with -march=native.

Protocol and options

UCI. Options: Hash (default 128 MB), Threads (default 1),
Move Overhead (default 30 ms), EvalFile (default <embedded>),
Use NNUE (default true), Use Policy (default false).

The engine does not learn between games and writes no persistent state.
There is no opening book in the binary.

Verification

printf 'uci\nisready\nposition startpos\ngo depth 13\n' | NARC-Next-4.1-x86-64-v3.exe

Expected at depth 13 from the start position: score cp 37, nodes 168609,
bestmove e2e4.

Note: the search runs on a background thread. Sending quit immediately after
go aborts it before completion and returns the first legal move; allow the
search to finish, as any GUI does.

Provenance

No Stockfish source code is copied or linked. The NNUE network is trained by
knowledge distillation on Stockfish 18 evaluation labels; the optional root
policy network (disabled by default) on Stockfish 8 move choices. Full
disclosure in the README.

License: GNU GPL v3 or later.