Reckless is a UCI chess engine written in Rust as a personal project.

Guided by the insights from the chess programming community, it fearlessly combines established concepts, as the name suggests.

• Bitboards with Little-Endian Rank-File Mapping
• Magic Bitboards for sliding piece attacks
• Copy-Make approach

• Pseudo legal move generator
• Pre-calculated attack maps using Fancy Magic Bitboards
• Magic numbers are pre-generated using Reckless Magics
• Compile time generation of move maps using a build script

• Fail-Soft Alpha-Beta
• Principle Variation Search
• Iterative Deepening
• Aspiration Windows
• Transposition Table
• Quiescence Search

• Reverse Futility Pruning
• Null Move Pruning
• Futility Pruning
• Late Move Pruning
• Delta Pruning

• Late Move Reductions
• Internal Iterative Reductions

• Check Extensions

• Hash Move
• MVV-LVA
• Killer Heuristic
• History Heuristic

• NNUE
• Architecture: (768 -> 128)x2 -> 1
• Activation Function: CReLU
• Quantization: i16 (256/64)
• Trained on original data generated entirely through self-play

You can download precompiled builds from the GitHub Releases page.

• x86_64-v1: Slowest, compatible with any x86-64 CPU.
• x86_64-v2: Faster, requires support for POPCNT, SEE3, etc.
• x86_64-v3: Even faster, requires support for AVX2, etc.
• x86_64-v4: Fastest, requires support for AVX512.

For detailed information on the specific features needed for each level, refer to the x86-64 microarchitecture levels Wikipedia page.

To build the engine from source, make sure you have Rust 1.65 or a later version installed. If you don't have Rust, follow the official Rust installation guide.

Then, compile the engine using Cargo:

cargo rustc --release -- -C target-cpu=native

Alternatively, you can use the provided Makefile:

# Build for the current CPU architecture
make
# Build release binaries for all microarchitecture levels
make release

Reckless is not a standalone chess program but a chess engine designed for use with UCI-compatible GUIs, such as Cute Chess or ChessBase.

Alternatively, you can communicate with the engine directly using the UCI protocol.

Along with the standard UCI commands, Reckless supports additional commands for testing and debugging:

Contributions are welcome! If you encounter issues or have suggestions for improvements, please open an issue or submit a pull request.

• Chess Programming Wiki: A crucial resource that greatly contributed to the project's foundation.
• Cute Chess: The primary testing tool.
• Open source chess engines, like Stockfish, Ethereal, Berserk, and numerous others, for serving as inspiration and providing ideas that fuel development.
• Many thanks to the CCRL team and all chess engine testers for their valuable contributions.

This project is licensed with the MIT license.