Volkrix

Volkrix is a UCI chess engine written in Rust. It is a clean-room implementation focused on long-term strength, reproducibility, and open development.

Features

• Standard chess move generation with perft-verified legality
• Make/unmake with Zobrist hashing, repetition detection, and SEE
• Iterative deepening alpha-beta search with quiescence, PV tracking, aspiration windows, and quiet-move LMR
• Tapered classical evaluation: material, mobility, king safety, pawn structure, passed pawns, bishop pair, rook files, and lightweight threats
• Persistent transposition table with Hash / Clear Hash controls
• Lazy SMP via the Threads option
• Optional Syzygy tablebase probing (SyzygyPath)
• Optional NNUE evaluation (EvalFile) using the in-tree VOLKNNUE format
• Reproducible bench command tied to the real search

Building

Volkrix builds on stable Rust with no external chess crates in the engine core.

cargo build --release

The release binary is written to target/release/volkrix.

A small helper script wraps the common workflows:

python3 scripts/dev.py fmt
python3 scripts/dev.py clippy
python3 scripts/dev.py test
python3 scripts/dev.py bench
python3 scripts/dev.py release --target aarch64-apple-darwin

Usage

Volkrix speaks the Universal Chess Interface and works with any UCI-compatible GUI (Cute Chess, Arena, Banksia, etc.).

From a terminal:

$ volkrix
uci
position startpos moves e2e4 e7e5
go movetime 1000

Run a deterministic search benchmark:

volkrix bench

Supported UCI commands

uci, isready, ucinewgame, position, go, stop, quit.

go accepts depth, movetime, infinite, and the standard time-control fields (wtime, btime, winc, binc, movestogo).

Options

Option	Default	Description
Hash	16	Transposition table size in MB
Clear Hash	—	Button: clear the transposition table
Threads	1	Number of search threads (Lazy SMP)
SyzygyPath	""	Directory containing Syzygy tablebase files
EvalFile	""	Path to a VOLKNNUE network; empty uses classical eval

Malformed FEN strings, illegal moves, and malformed UCI input are rejected without panicking or corrupting engine state.

Releases

Publishing a GitHub Release triggers .github/workflows/release.yml, which builds volkrix and uploads per-platform archives to the release.

Project layout

src/        engine core (board, movegen, search, eval, UCI)
tools/      offline tooling, including the NNUE packer
trainer/    NNUE training pipeline
benches/    Criterion benches
tests/      integration and perft tests
docs/       design notes

Further reading lives in docs/:

• architecture.md — module layout and data flow
• search.md — search algorithm details
• perft.md — move generation verification
• nnue-training.md — NNUE training and packing workflow
• roadmap.md — planned work

Clean-room provenance

Volkrix is an independent clean-room implementation. GPL-licensed engine code, machine translations, or close paraphrases of GPL sources must not be copied into this repository. Contributors may study public papers, algorithms, and high-level descriptions, but implementation must be written from scratch.

License

Dual-licensed under either of:

• MIT license (LICENSE-MIT)
• Apache License 2.0 (LICENSE-APACHE)

at your option.