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Fairy-Stockfish 13.1

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@ianfab ianfab released this 13 May 13:38
· 395 commits to master since this release

This release adds support for up to 26 custom piece types per user-defined variant.


  • Custom piece types
  • New base piece movements
    • Nightrider
    • Diagonal cannon
    • Grasshopper
    • Limited distance sliders
  • Variants
    • Nightrider
    • Grasshopper
    • TenCubed
    • Yari, Tori, and Okisaki shogi


  • Small speed improvements for all variants
  • Significant playing strength improvement in bughouse against human opponents by considering drops of pieces from anticipated piece flow.


  • Fix atomic castling rules for one corner case to ensure compatibility with lichess rules.
  • Use correct rank numbering for en passant field in Grand chess FENs in CECP protocol.
  • Disambiguate castling moves in variants where the king only moves one square to castle.

Files of the release

  • .exe are Windows executables, the files without extensions are Linux binaries.
  • Versions containing largeboard have support for board sizes >8x8 (e.g., Xiangqi, Shogi), the others are faster but have less variants.
  • Use bmi2 versions for best performance on modern hardware, or fairy-stockfish-largeboard_x86-64.exe for best compatibility.
  • The variants.ini contains documentation and examples how to configure user-defined variants and pieces.

Thanks to all code contributors, fishtest contributors, and supporters for their contributions to this release.