Codex Gamicus

ChessV (short for Chess Variants) is a free computer program designed to play a large number of chess variants. ChessV is an open-source, universal chess variant program with a graphical user-interface, sophisticated AI, support for opening books and other features of traditional chess programs. The developer of this program, Gregory Strong, has been adding more variants with each release of ChessV. Currently, over 50 chess variants are supported. ChessV is designed to be able to play any game that is reasonably similar to Chess. ChessV is one of only a few such programs that exist. The source code of this program is freely available for download as well as the executable program.

As of ChessV 0.93, it is possible to customize the variants it supports. Of all chess variants currently supported, two of the most-played variants are probably Fischer Random Chess and Grand Chess.

ChessV is currently capable of playing:

  • 2 variants on 6×6 squares
  • 17 variants on 8×8 squares
  • 15 variants on 10×8 squares

(including 10 Capablanca Chess variants)

  • 15 variants on 10×10 squares
  • 3 variants on 12×8 squares

Some of the provided variants can be customized in their details. It is also possible to create custom variants with ChessV 0.93. While the board sizes have to be 6×6, 8×8, 10×8, 10×10 or 12×8 and the pieces in a custom variant have to be chosen from a limited list, this allows ChessV to play hundreds or thousands of variants of each game it directly supports.

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.

Current limitations[]

  • No games with more than two players are supported.
  • No game with a move order other than the usual white-black is supported (such as double-move chess).
  • No games with randomness or hidden information are supported.
  • No ability to edit the board mid-game is provided. This is under development.

Supported games[]

Alapo, Almost Chess, Angels & Devils, Archchess, Berolina Chess, Bird's Chess, Cagliostro's Chess, Capablanca Chess, Capablanca Chess (Aberg variant), Capablanca Chess (Paulowich variant), Carrera's Chess, Chess, Chess480, Chess with Augmented Knights, Chess with Different Armies, Chess with Ultima Pieces, Courier Chess, Cylindrical Chess, Diagonal Chess, Diamond Chess, Embassy Chess, Emperor's Game, Eurasian Chess, Extinction Chess, Fischer Random Chess, Great Chess, Great Shatranj, Grand Chess, Grotesque Chess, Janus Chess, Janus Kamil Chess, Kinglet, Ladorean Chess, Legan's Game, Lions and Unicorns Chess, Los Alamos Chess, Modern Kamil, Modern Shatranj, Odin's Rune Chess, Opulent Chess, Polymorph Chess, Roman Chess, Royal Court, Schoolbook Chess, Shatranj, Shatranj Kamil, Shatranj Kamil (64), Sosarian Chess, Switching Chess, TenCubed Chess, Three Checks Chess, Ultima, Unicorn Chess, Unicorn Great Chess, Unicorn Grand Chess, Univers Chess.


ChessV software won third place in a 2004 Gothic Chess Computer World Championship [1][2]

See also[]


  1. The 2004 Gothic Chess Computer World Championship by Ed Trice
  2. Trice E (Dec 2004). "The 2004 Gothic Chess Computer World Championship". ICGA Journal 27 (4): 249–254. 

External Links[]