ChessV (short for Chess Variants) is an open source program to play many chess variants. Of the many chess variants it supports, the most popular are probably Fischer Random Chess and Grand Chess. Furthermore this program (which is often upgraded, version 0.72 is described here) is capable of playing:

• two variants on 6 x 6 squares
• ten variants on 8 x 8 squares
• four main variants on 10 x 8 squares, further more popular Capablanca sub variants like Birds Chess
• three variants on 10 x 10 squares
• six variants of historical variants of the todays most popular kind of chess (played since about 1700)
• a strange but (relatively) popular Cylindrical Chess
• more options are available

Playing strength

At the Computer Gothic Chess® World Championship of 2004, which indeed represented a great challenge for chess variant programmers, ChessV finished, despite a few weak points (especially in the handling all possible endgame scenarios such as recognizing unforced draws), with a remarkable third place after 14 rounds.

ChessV is a program comparable in some ways and in the same class as Zillions of Games, a commercial, high quality universal board game engine.

Engine Features

Searching: Alpha-Beta Nega-Max Principal Variation search, Iterative Deepening, Null-move Forward Pruning, Static Exchange Evaluation (SEE), Search Extensions: check extension, recapture extension, null-move threat extension, PV extension, Futility Pruning and Razoring, History Heuristic, Killer-move Heuristic.
Evaluation: Piece-square tables, Pawn structure evaluation, Mobility evaluation, King Safety, King Tropism, Lazy Evaluation.
Hash Tables: Transposition Table, Pawn Structure Table, Evaluation Cache, Repetition Detection.

External links

• sourceforge.net (home of the project on SourceForge, with executables and source code)
• gregstrong.com (homepage of the author, with information about this and other projects)
• brainking.com (a chess variants server to play against other human beings)