thunfisch

Thunfisch is a UCI-compatible chess engine written from scratch in Rust. It uses magic‐bitboard move generation, iterative deepening with alpha-beta and quiescence search and a transposition table. For evaluation, Piece-Square Tables are used.

It is a listed Bot-Account on Lichess. If it is online you can challenge it here.

Build Features

For easy isolation of individual engine features, these have been added as compiler features to the project. See Cargo.toml for what features are available, and settings.rs for how they relate to the code.

Building with all features

cargo build
# or: cargo build --features all

Building with only specific features

For example, say you want only Quiescence Search, Alpha Beta and MVV-LVA move ordering enabled. Then run this command:

cargo build --no-default-features --features "ab,qs,mvv-lva"

How to Play Locally

Thunfisch is a command-line application that implements the Universal Chess Interface (UCI). To play against it comfortably, you should load the compiled binary into a chess GUI. We recommend Cutechess. There are instruction on how to add the bot to the gui here.

General Setup Steps:

1. Build the engine using cargo build --release.
2. Locate the compiled executable at target/release/thunfisch (or thunfisch.exe on Windows).
3. Open your preferred chess GUI and look for an "Add Engine" or "Manage Engines" option in the settings.
4. Point the GUI to the executable file. You can then start a new game and select Thunfisch as your opponent.

Codebase Overview

• src/types/: Core data structures representing the chess board, pieces, bitboards, and moves.
• src/move_generator/: Logic for generating legal chess moves efficiently using magic bitboards and pre-calculated masks.
• src/search/: The primary chess intelligence containing alpha-beta pruning, iterative deepening, quiescence search, move ordering, and the static evaluation function.
• src/utils/: Helper functions including make/unmake move mechanics and Zobrist hashing for the transposition table.
• src/communication/: UCI protocol parser and FEN string handling.
• src/debug/: Performance testing (perft) algorithms and visualization tools for debugging the board state.
• python-debugging/: Python scripts for advanced visualization, depth/time plotting, and log analysis.
• testing/: Scripts for engine match testing (SPRT).

Commands

Basic commands
  uci                - Identify engine and author
  isready            - Engine readiness check
  ucinewgame         - Start new game (resets engine state)
  position [options] - Set up position (see below)
  go [parameters]    - Start search (see below)
  quit               - Exit engine
  fen                - Print current FEN

position options
  startpos           - Set up the standard chess starting position
  fen <FEN>          - Set up a position from a FEN string
  moves <m1> <m2>    - Play moves from the given position

go parameters:
  depth <n>          - Search to fixed depth n (plies)
  wtime <ms>         - White time left (ms)
  btime <ms>         - Black time left (ms)
  winc <ms>          - White increment per move (ms)
  binc <ms>          - Black increment per move (ms)
  movestogo <n>      - Moves to next time control
  movetime <ms>      - Search exactly this many ms

perft commands:
  go perft <depth> [--debug|--perftree|--rayon]
    --debug     - Print debug info for perft
    --perftree  - Print perft formatted for perftree
    --rayon     - Use rayon for parallel perft

Examples:
  position startpos moves e2e4 e7e5
  go depth 6
  go wtime 60000 btime 60000 winc 0 binc 0
  go perft 7 --rayon

Debugging:
  draw               - Print board
  moves              - Print legal moves
  eval               - Prints current Evaluation with Depth of 0
  do <move>          - Play move (e.g. do e2e4)
  pinmask            - Show pin masks
  checkmask          - Show check mask
  attackmask         - Show attack mask
  empty              - Empty Squares Bitboard
  white              - White Squares Bitboard
  black              - Black Squares Bitboard
  occupied           - Occupied Squares Bitboard
  hash               - Current board hash

Development Quickstart

1. Clone the repository

   git clone https://github.com/Kaynoux/thunfisch.git
   cd thunfisch

2. Run the tests

   cargo test --release

3. Run the engine

   cargo run --release

License

This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for details.