# ChessV

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Computer program designed to play chess variants

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ChessV Two engines playing Capablanca chess in ChessV 2.2 Developer Gregory Strong Stable release 2.2 / January 22, 2020; 6 years ago (2020-01-22) Operating system Windows Type Computer chess License GPL Website http://www.chessv.org

**ChessV** (short for Chess Variants) is a [free](/source/Free_software) [computer program](/source/Computer_program) designed to play many [chess variants](/source/Chess_variant). *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*. Over 100 chess variants are supported, including the developer's few own variants[1] and other exotic variants, and can be programmed to play additional variants. *ChessV* is designed to be able to play any game that is reasonably similar to [chess](/source/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 supported, two of the most-played variants are probably [Fischer Random Chess](/source/Fischer_Random_Chess) and [Grand Chess](/source/Grand_Chess).

*ChessV* is 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](/source/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. While users can create custom variants with ChessV 0.93, it needs to be recompiled, which is tedious when programming. ChessV 2.0+ fixes this, using a scripting language. While 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](/source/Search_algorithm)**: [Alpha-Beta](/source/Alpha-beta_pruning) [Nega-Max](/source/Negamax) Principal variation search, [Iterative deepening](/source/Iterative_deepening_depth-first_search), [Null-move](/source/Null-move_heuristic) Forward [Pruning](/source/Branch_and_bound#General_description), [Static Exchange Evaluation](https://en.wikipedia.org/w/index.php?title=Static_Exchange_Evaluation&action=edit&redlink=1) (SEE).

- - *Search Extensions*: [check](/source/Check_(chess)) extension, recapture extension, null-move threat extension, PV extension, Futility Pruning and Razoring, History [Heuristic](/source/Heuristic), [Killer-move heuristic](/source/Killer_heuristic).

- **Evaluation**: [Piece](/source/Chess_piece)-square tables, [Pawn](/source/Pawn_(chess)) structure evaluation, Mobility evaluation, [King](/source/King_(chess)) safety, King tropism, [Lazy evaluation](/source/Lazy_evaluation).

- **[Hash Tables](/source/Hash_table)**: [Transposition table](/source/Transposition_table), Pawn structure table, Evaluation [cache](/source/Cache_(computing)), Repetition detection.

Since ChessV 2.2, the engine can be set to adjust to their player's needs:

- **Transposition Table Size** can be adjusted.

- The engine can be allowed for **variance of play**.

- **Weaken** the chess engine to be human-beatable even for beginners.

## Current limitations

- No games with more than two players are supported.

- No games with randomness or hidden information are supported.

- No ability to edit the board mid-game is provided.

## Supported games

A game of "Chess and a Half" played on ChessV 0.9 (old)

ChessV supports many variants. Other than chess, it supports:

- [Alice Chess](/source/Alice_Chess), [Almost Chess](/source/Almost_Chess), Archchess, [Berolina Chess](/source/Berolina_chess), Bird's Chess, Capablanca Chess and its variants, Carrera's Chess, [Chess480](/source/Chess960), Chess and a Half,[2] [Chess with Different Armies](/source/Chess_with_different_armies), [Courier Chess](/source/Courier_Chess), [Cylindrical Chess](/source/Cylinder_chess), Diagonal Chess, Diamond Chess, [Doublemove chess](/source/Double_move_chess), [Embassy Chess](/source/Embassy_Chess), Eurasian Chess, [Extinction Chess](/source/Extinction_chess), [Fischer Random Chess (Chess960)](/source/Chess960), Great Chess, Great Shatranj, [Grand Chess](/source/Grand_Chess), Grotesque Chess, [Janus Chess](/source/Janus_Chess), [Kinglet](/source/Kinglet_Chess), Ladorean Chess, Legan's Game, [Los Alamos Chess](/source/Los_Alamos_chess), [Makruk](/source/Makruk), [Omega Chess](/source/Omega_Chess), Opulent Chess, Roman Chess, Royal Court, [Shatranj](/source/Shatranj), [Shatranj Kamil](/source/Tamerlane_Chess), Sosarian Chess, Switching Chess, TenCubed Chess, [Three Checks Chess](/source/Three_checks_chess), and more infamous variants.

Since ChessV can be programmed to play additional variants, here are a few examples:

- [Almost Chess](/source/Almost_Chess), Enep, Butterfly Chess,[3] [Nightrider](/source/Nightrider_(chess)) chess and Janus Kamil.

## Syntax

ChessV code is saved as the extension ".cvc" (ChessV Code). Its syntax is reasonably similar to [C#](/source/C_Sharp_(programming_language)). The scripting language is mostly stable, but creating new rules for new pieces is not supported yet. Here is an example of "Almost Chess" in .cvc code:

Game 'Almost Chess' : Chess
{
	Invented = "1977";
	InventedBy = "Ralph Betza";

	AddPieceTypes
	{
		Queen.Enabled = false;
		AddPieceType( Chancellor, "Chancellor", "C", 900, 925 );
	}

	SetGameVariables
	{
		Array = "rnbckbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBCKBNR";
		PromotionTypes = "CRNB";
	}
}

## Competitions

ChessV software won third place in a 2004 Gothic Chess Computer World Championship.[4][5]

## See also

- [Chess engine](/source/Chess_engine)

- [Computer chess](/source/Computer_chess)

- [Fairy-Max](/source/Fairy-Max)

- [List of chess software](/source/List_of_chess_software)

## References

1. **[^](#cite_ref-1)** ["Opulent Chess"](https://www.chessvariants.com/rules/opulent-chess). *The Chess Variant Pages.*

1. **[^](#cite_ref-chv_2-0)** [https://www.chessvariants.com/rules/chess-and-a-half](https://www.chessvariants.com/rules/chess-and-a-half) Chess and a Half,

1. **[^](#cite_ref-3)** [https://www.chessvariants.com/invention/butterfly-chess](https://www.chessvariants.com/invention/butterfly-chess) Butterfly Chess

1. **[^](#cite_ref-4)** The 2004 Gothic Chess Computer World Championship by Ed Trice [http://www.chessville.com/GothicChess/ComputerWorldChampionships.htm](http://www.chessville.com/GothicChess/ComputerWorldChampionships.htm)

1. **[^](#cite_ref-5)** Trice E (Dec 2004). "The 2004 Gothic Chess Computer World Championship". *ICGA Journal*. **27** (4): 249–254. [doi](/source/Doi_(identifier)):[10.3233/ICG-2004-27414](https://doi.org/10.3233%2FICG-2004-27414).

## External links

- [ChessV download page](http://www.chessv.org)

- [site about Chess Variants, mentions ChessV in several articles](http://www.chessvariants.org)

v t e Chess variants (list) Orthodox rules Different starting position Fischer random chess Displacement chess Transcendental chess Different number of pieces Dunsany's chess Handicap Unorthodox board Balbo's game Circular chess Cylinder chess Double chess Grid chess Hexagonal chess (Cross chess, Masonic chess) Infinite chess Millennium 3D chess Minichess (Los Alamos chess) Rhombic chess Spherical chess Three-dimensional chess Triangular chess Unorthodox rules with traditional pieces Standard 8×8 board Andernach chess Atomic chess Beirut chess Checkless chess Chessplus Circe chess Crazyhouse Cubic chess Dynamo chess Extinction chess Hostage chess Knight relay chess Legan chess Losing chess Madrasi chess Monochromatic chess Patrol chess Portal chess Progressive chess Three-check chess Way of the Knight Multimove variants Avalanche chess Kung-Fu Chess Marseillais chess Monster chess Progressive chess Elements of chance Dark chess Dice chess Knightmare Chess Kriegspiel Penultima Unorthodox rules on an unorthodox board 5D Chess with Multiverse Time Travel Alice chess Apocalypse Chad Chessence Congo Diplomat chess Dragonfly Jeson Mor Parallel worlds chess Rollerball Unorthodox rules using non-traditional pieces Standard 8×8 board Baroque Berolina Chakra Chess with different armies Duell Falcon–hunter chess Grasshopper chess Musketeer chess Pocket mutation chess Cheskers Compound pieces Almost chess Capablanca Chess Capablanca random chess Gothic chess Grotesque chess Ladorean chess Maura's Modern chess Schoolbook chess Seirawan chess Univers chess Chancellor chess Grand Chess Embassy chess Janus Chess Maharajah and the Sepoys Modern chess Tutti-frutti chess Unorthodox boards and pieces 2000 A.D. Chesquerque Chess on a really big board Courier-Spiel Dragonchess Gess Omega Chess Stratomic Dekle's triangular chess Wildebeest chess Wolf chess Multiplayer Bosworth Bughouse chess Business chess Djambi Duchess Enochian chess Forchess Fortress chess Four Fronts Four-player chess Gala Hand and brain Quatrochess Superchess Three-man chess Three-player chess Tri-chess Inspired games Arimaa Camelot Jetan Martian Chess Navia Dratp The Duke Chess-related games Historical Chadarangam Chaturaji Chaturanga Courier chess Grant Acedrex Semedo Shatranj Short assize Great chess Tamerlane chess Great chess Completed Turkish Great chess Regional Janggi variants Makruk Senterej Shatar Shatra Shogi Chu shogi Dai shogi Other variants Sittuyin Xiangqi Jungle Banqi Manchu chess Game of the Three Kingdoms Game of the Three Friends Game of the Seven Kingdoms Other variants Software ChessV XBoard Fairy-Max Zillions of Games Related Correspondence chess Fairy chess Fairy chess piece Fairy Chess Review The Chess Variant Pages Checkers

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