Anodos is a UCI-compatible chess engine written in Rust. Built from scratch with bitboard-based move generation and alpha-beta optimised search.

• Move generation
  • Bitboards for pseudo-legal move generation
  • Fancy magic sliding piece attacks
• Search
  • Iterative deepening
  • Aspiration windows
  • Negamax with alpha/beta pruning
  • Null-move pruning
  • Extended/reverse futility pruning
  • Late move pruning/reductions
  • Internal iterative reductions
  • Principal variation search
  • Quiescence search with SEE/delta pruning
  • Check extension
  • Transposition table with Zobrist keys
  • Move ordering
    • TT move
    • SEE + MVV/LVA
    • Killer moves
    • History heuristic
• Handcrafted evaluation
  • Game-phase tapering
  • Material counting
  • Piece-square tables
  • Piece mobility
  • King safety with pawn-shield scoring
  • Doubled, isolated and passed pawns
  • Open and half-open files for rooks
  • Insufficient material draw detection
• Time management
  • Soft limits based on PV stability and eval volatility
• Universal Chess Interface
  • Play via any UCI-compatible GUI (e.g. Cute Chess, En Croissant)

• Search
  • Mate distance pruning
  • Counter-move heuristic
  • Reductions for late/bad captures
  • Staged move generation
  • Singular extensions
  • TT eval caching
  • TT bucketing
  • TT prefetching
  • Multi-threading / Lazy SMP
• Evaluation
  • Pawn hash table
  • Syzygy tablebase support
  • Replace HCE with NNUE
• Time management
  • Soft limits based on search tree node distribution

Supported commands:

uci
isready
ucinewgame
position startpos [moves ...]
position fen <fen> [moves ...]
go [infinite]
go depth <n>
go mate <n>
go nodes <n>
go movetime <ms>
go wtime <ms> btime <ms> [winc <ms>] [binc <ms>]
setoption name Hash value <MB>
stop
quit

Beyond the UCI protocol, the engine supports these debugging/utility commands:

This project uses Rust edition 2024, so you'll need Rust 1.85+ (stable).

For the best performance, always use release mode:

cargo build --release
./target/release/anodos

Alternatively, you can run in release mode directly:

cargo run --release

To enable debug assertions (useful during development for catching bugs), use:

cargo run

Only use debug mode for testing and development; release mode is strongly recommended for actual games or benchmarks.

Binaries published on the Releases page are built with PGO (see .github/workflows/release.yml).

To run a local PGO build:

rustup component add llvm-tools-preview
cargo install cargo-pgo

# Build an instrumented binary
cargo pgo build

# Collect profiles by running the benchmark command
cargo pgo run -- bench

# Build the optimised (PGO) binary
cargo pgo optimize

Run the test suite:

cargo test

This includes a shallow perft check from the starting position (depth 5).

To run the deeper perft test suite (ignored by default), include ignored tests and use release mode:

cargo test --release -- --include-ignored

To measure the engine's nodes-per-second performance, run the binary as follows:

./anodos bench [--depth <DEPTH>] [--tt-mb <MB>]

• --depth (default: 13) sets the search depth for each position
• --tt-mb (default: 64) sets the transposition table size in MB