The Calculon Chess Engine.

Calculon is a chess game written in Java. The code base is getting relatively mature - all aspects of the game are currently handled including draws based on the 50 move rule and threefold repetition.

Most work is currently going into performance - the speed is up from around 500k nodes/sec (nps) in v0.2 to 2.1M nps in v0.3 (Crafty does 14M nps on the same platform). LATEST: A refactoring to completely use the bitboard code now hits > 5.5M nps - not too bad for a Java implementation!

The next stage of the project will be to add quiescence searching as the engine has pretty much reached the limits of what can be done by brute force searching. Also, the evaluation logic needs to be looked at further.

The current version can be found playing via AJAX at http://calculonxweb.appspot.com and also on the Internet Chess Club at http://www.chessclub.com as CalculonX, where it currently as a rating around 1400 in standard, blitz and bullet categories.

See also, the web interface project at http://code.google.com/p/calculonxweb and the version for mobile phones at http://code.google.com/p/calculonxme