Devlog 0x10 - Kirin Chess v0.0.1 Release

Today, I will be talking about the current state of Kirin, existing issues, as well as officially releasing a working, chess playing binary.

Chess Playing Binary Release

Today, I released the first Kirin Chess binary, which is available on Github. If you're interested in playing against Kirin, you can download the binary and use a chess GUI like Arena or check out the official KirinChessBot on Lichess!

No promises that the Lichess bot will be online right now, but in the next week or two I will try and get it running on my home server so that it is available 24/7.

Future Improvements

The most immediate improvement is to enhance the search algorithm with additional pruning techniques. While Kirin has Late Move Reduction, history pruning, and null move pruning, adding features like futility pruning and razoring would significantly improve search efficiency. Null move pruning is particularly important as it can dramatically reduce the search space in positions where one side is clearly better. Additionally, implementing aspiration windows will help make better use of the alpha-beta bounds.

The evaluation function should also probably be expanded to include more sophisticated positional understanding. Adding pawn structure evaluation (isolated pawns, doubled pawns, passed pawns), king safety assessment, and mobility evaluation would give Kirin better strategic understanding. I might also want to implement piece mobility evaluation and bishop pair recognition. Another valuable addition would be pattern recognition for common endgame positions like king and pawn vs king.

For engine infrastructure, implementing a proper opening book system would also be valuable. This would give Kirin strong play in the opening without spending search time, and help it avoid common opening traps. I will also likely add support for tablebase probing, starting with Syzygy endgame tablebases for 3-4 piece positions. This would give your engine perfect play in these endgame positions.

Performance optimization could be enhanced by implementing multi-threaded search (parallel search at the root level), better move ordering heuristics like SEE (Static Exchange Evaluation), and internal iterative deepening. The last thing I might also want to add support for is pondering (thinking on opponent's time) and more sophisticated time management, including detecting critical positions where more time should be spent.

Kirin's Current State

Board Representation

  • Bitboard-based representation for efficient move generation and board manipulation
  • Full support for all chess pieces, including special moves like en passant and castling
  • Support for standard chess FEN notation parsing and position setup

Move Generation

  • Legal move generator for all piece types
  • Special move handling (castling, en passant, promotions)
  • Pseudolegal move generation with immediate legality testing
  • Discovery check detection (broken)
  • Double check support (broken)

Search Algorithm

  • Principal Variation Search (PVS) implementation
  • Iterative deepening framework
  • Late Move Reduction (LMR) for search optimization
  • Transposition table for position caching
  • Quiescence search for tactical stability
  • Move ordering with MVV-LVA (Most Valuable Victim - Least Valuable Attacker)
  • History heuristic for move ordering
  • Killer move heuristic

Evaluation

  • Material scoring
  • Piece-square tables for positional evaluation
  • Separate evaluation for different game phases
  • Support for handling endgame positions

Engine Infrastructure

  • UCI (Universal Chess Interface) protocol support
  • Time management system
  • Support for various search controls (depth, nodes, time)
  • Debug capabilities and board visualization
  • Performance testing (perft) implementation

Performance Optimizations

  • Magic bitboard implementation for sliding piece move generation
  • Pre-calculated attack tables
  • Efficient bit manipulation techniques
  • Move generation optimizations
  • No dynamic memory allocation, stack only

Technical Features

  • Written in modern Zig (version 0.14)
  • Memory-efficient design
  • Type-safe implementation
  • Error handling using Zig's error system