Chess Variant Applets

by Ed Friedlander

I programmed these to show some of the many chess variants, rather than to be strong opponents. I could have added longer look-aheads, but this would have caused delays and taken up too much memory. Other chess applets exist and are also weak. Some of these applets recognize draw by repetition / perpetual check. Others fail to do so; again this is to save space and loading time.

The applet at André Heuner's Site is much stronger than mine. He also has some variants

I have tried to choose the ones that are actually popular with players. I welcome your suggestions. Green stars mark those that are very easy to learn and play casually.

I am presently looking for a Java programmer who can help me develop these into a site where people can play one another online. I expect to have access to an in-house server where I can run a Java server application sometime later this year.

There are also variants on checkers, including Byelorussian Cheskers. You can find these at other sites.

Easy Chess	Standard game
Absorption Chess	Capturer gains movement abilities
Absorption Chess II	Capturer gains movement abilities. This applet extends this to kings and pawns.
Abstract Chess	A friendly unit may donate some of its power to a neighbor.
Accelerated Chess	Two non-capturing moves, or one capturing move, each turn.
Active Chess	Two queens, 9x8.
Actuated Rotating Center Chess	Center rotates, you choose when and how.
Advance Chess	Pawns begin on third and sixth ranks
Airplane Chess	Large variant with airplanes which capture by landing just beyond an enemy unit.
Akenhead's Chess	Chinese pieces and Berolina pawns.
Alapo	Simple chess-like game.
Alice Chess	Looking-glass boards. Extremely popular variant.
Alice Chess II	Players begin on opposite boards.
Ms. Alice Chess	Units may make a "zero move" to the other board.
Alliance Chess	Two boards, four players, team wins by checkmating the primary player.
All-In Chess	Move either side's units. No reversing the previous move.
All-Mate Chess	Capture a piece only by rendering it unable to avoid FIDE capture.
Almost Chess	The queen may move as a knight or rook but not as a bishop.
Alternation Chess	You alternate your moves with a partner.
Amazon Chess	The queen may also move as a knight
Amazon Knights Chess	The queen may also move as a knight, and rooks and bishops are replaced by knights.
Ambi-Chess	Large board with two kings, move a member of each of two armies each turn.
Ambi-Chess II	As above, but you must escape check on the first of your two moves.
Angel Chess	9x8 board. Angels (Q+N) are difficult to exchange.
Annihilation I	Capture all non-royal units without checking the king.
Annihilation II	Capture all enemy units except the uncapturable king.
Anti-Gravity Chess	A newly-moved unit repels the nearest unit along each orthogonal line.
Anti-King Chess	Your anti-king unit must remain under enemy attack. Berolina pawns an an unusual setup.
Anti-King Chess II	Your anti-king unit must remain under enemy attack. Usual setup plus anti-king.
Anti-Magnetic Chess	Like colors attract, opposites repel, along orthogonal lines.
Anticipation Chess	Commit after moving to which kind of unit you will move next.
Antipodean Chess	Captured units move, if possible, to the square four ranks and four files away.
Antipodean Chess II	Antipodean move can queen a pawn.
Anywhere Chess	Units other than the king may make non-capturing moves to any square.
Variant I: Nearly Anywhere	I. May check only by a normal move
Variant II: Parachute Anywhere	II. May attack only by a normal move
Variant III: Hardly Anywhere	III. May attack or escape from check only by a normal move
Apocalypse Chess	Miniature version with four horsemen.
Archimedes Chess	Capture by attacking an enemy unit with two of yours.
Arena Chess	Entry in the 32-move-maximum contest.
Alternating Chess III	Each side alternates between moving pawn and piece. Pritchard says this may come from Argentina.
Arktur Chess	Random first ranks, two kings.
Arrow Pawn Chess	Pawns do not promote but have expanded moves.
Assassin Chess	Shoot chess without royalty and with pawns that cannot be shot by line movers.
Assault Chess	Play twice; which can win as White against a weakened Red faster?
Atlantis Chess	You may sink an edge square instead of moving a unit
Atomic Pawn Chess	One time in ten, a pawn explodes just after moving
Avalanche Chess	Advance the opponent's pawns. Popular variant.
Avalanche Chess 2	As before, except that the red king and queen are switched. Some say this makes a better game.
Aviation Chess	Knight pawns move and capture as bishops and can leap any number of units
Bachelor Chess	All pieces promote. Win in the usual way or by joining king and queen.
Bachelor Chess 6x7	Original version on 6x7 board.
Balaklava Chess	All non-royal units can make non-capturing knight moves
Balbo Chess	Odd-shaped board, bishops as powerful as knights.
Bank of Scotland	Scotch Progressive Chess, with an extra move per turn for each time your side has checked the opponent.
Main Branch	Only a check ends a sequence early.
Modern Branch	A check or a move to a square under attack both end a sequence early.
Bankhouse Chess	Buy units back from the opponent, or bribe units you have captured to change sides.
Barasi Chess	Pieces cannot move backwards; pawns are Berolina
Bastardo	Four players, each playing alone, on an ordinary board
Bastardo Hallowe'en	Specter kings, death knights, plague pawns and bishops.
Bastardo for President	Royalty is assigned at random and kept secret
Dynamic Bastardo	Bastardo, load your initial setup
Objective Bastardo	Each player is given a different, distinct advantage.
Batak Chess	Indonesian culture where chess is very popular
Battle Chess	Move as many of your units as you like, once each, each turn. Win by capturing the enemy king.
Bear Chess	Russian variant with new piece
Beirut Chess	One unit is secretly carrying a bomb
Benedict Arnold Chess	No captures, but units attacked by the mover are flipped.
Bennie Prince's Chess	Units not under attack may be removed and returned, one at a time
Berolina Chess	Pawns move diagonally and capture straight ahead
Berolina Grid Chess	Popular with NOST.
Besiege Chess	Large variant with White on either side, Black in center
Bicapture Chess	You may capture, and be checked by, your own units
Big Board Chess	Large set with setup phase.
Billiards Chess	Bishops and queens bounce off the edges
Bird's Chess	Large variant by the grandmaster
Bishop Chess	Bishops do not capture and cannot be captured. Win by getting your bishop to the end rank.
Black and White Chess	Two moves per turn, the first from a white square, the second from a black square.
Blackburne's Proposal	QR becomes a marshall, QB becomes a pegasus, and KB becomes a queen are enhanced.
Blackjack Chess	If the point value of your remaining units totals 21, you win.
Black Hole Chess	Units falling into the central black hole may be recovered.
Blind Shogi	Japanese kriegspiel.
Blockade Chess	A unit may only capture one of its own kind. Popular at U. of Oslo.
Blood Brothers Chess	Pieces defend others of their kind regardless of location.
Blue Chess	Commemorates Deep Blue vs. Kasparov.
Bomb Chess	Queen's Rook moves as king and can explode
Bomber Chess I	Pawns can be made to explode.
Bomber Chess II	Pawns can be made to explode, and always explode when captured.
Bomber Chess III	Pawns and pieces can be made to explode.
Booster Pawn Chess	Pawns push friendly pieces.
Brickchucking Chess	Pieces can only move forward, but attack the king in any direction.
Brusky Hexagonal Chess	Hexagonal variant from the 1960's.
Brotherhood Chess	A piece cannot capture one of its own kind.
Buczo's Chess	10 x 10 variant with optional underpromotion
Bug Eyed Monster Chess	A non-royal unit may make any move which, in FIDE chess, some other unit could make and it could not make.
Bughouse Chess	Two boards. Units captured move to opposite board. Popular variant.
Burmese Chess	Most popular form in Burma.
Butters Chess	Capture by moving adjacent rather than by displacement.
Byzanatine Chess	Circular 16x4 Shatranj variant.
Byzanatine Chess II	A different account of the old circular game.
Caissa	Christiaan Freeling's game with a royal queen.
Cambodian Chess	Historic 9x9 game.
Canadian Chess	Captured units are replaced immediately. Not really a Canadian regional game.
Canadian Chess II	Queens are replaced as rooks, rooks as bishops, etc. Pawns are not replaced.
Canadian Progressive Chess	Usually Canadian Chess is played progressively.
Cannon Chess	Rooks and Bishops move and capture after the style of Chinese cannons.
Capablanca Chess	8x10 board variant by the grandmaster.
Capablanca Chess 10x10	10x10 board variant by the grandmaster.
Capapranka Chess	A cap renders a square and any occupant non-functional.
Capped Pawn Chess	White must checkmate with a move of the KBP or lose. The toughest odds given in chess.
Capricorn Chess	Rooks capture by moving adjacent to enemy units.
Capture the Flag Chess	As in the kids' tag game
Capturing Progressive Chess	Scotch Chess, but if no capture is made the count drops back to one
CardChess	Proprietary game with board 10x10 and four suits of chess cards. Many different games are possible.
CardChess for Two	Faster than orthochess.
CardChess for Three	Survivor wins.
CardChess for Four	All-play-all.
Team CardChess	Four players, two teams.
Memory CardChess for Two	Faster than orthochess.
Memory CardChess for Three	Survivor wins.
Memory CardChess for Four	All-play-all.
Team Memory CardChess	Four players, two teams.
Non-Random CardChess for Two	Faster than orthochess.
Non-Random CardChess for Three	Survivor wins.
Non-Random CardChess for Four	All-play-all.
Team Non-Random CardChess	Four players, two teams.
Carnivore Chess	Each turn, also move an uncapturable predator.
Carrera Chess	10x8 version described in 1617
Cavalier Chess	All units except the queen enhanced knight-like.
Cavalry Chess	Enhanced moves for all pieces
Centerless Chess	No center pawns or squares
Central Chess	Move twice per turn, once in center and once on edge
Chad	Christiaan Freeling's simple game of complex strategy.
Chameleon Chess	Begin with 16 pawns which evolve.
Chance Chess	Classic proprietary game. Randomizer determines what unit(s) you may move. Free move out of check.
Chancellor Chess	Classic 9x9 board with rook-knight.
Chaos Chess	Random starting positions
Chatty Chess	Four-handed game using normal board and pieces
Chaturanga	Oldest known form of chess
Chaturanga for Four	Ancient partnership game, sometimes said to be the oldest form of chess. I have presented a modern version played in India in recent times.
Chaturanga for Four -- Machiavellian Version	Cutthroat new version.
Chazz	King and pawns
Cheapmate Chess	You may make one illegal move in order to checkmate.
Cheapo	Once during the game, you can move a unit twice
Checkers Chess	Pieces may not move backwards until they have visited the opposite side of the board.
Check Force Chess	The player giving check decides how the opponent escapes.
Checkless Chess	You may not check unless it is mate.
Chelma	Chess-Halma combination with no royal unit.
Chesapeake Four-Handed Chess	Based on Chessapeak Challenge, arguably the best commercial four-player chess game.
Cheshire Cat Chess	When a unit leaves a square, the square vanishes.
Cheshire Cat Chess, 10 x 10	When a unit leaves a square, the square vanishes.
Cheskers	The most popular cross between checkers and chess.
Chess Addresses	Place the enemy units, then return your own to their squares of origin.
Chess Draughts	Captures are mandatory; a unit which can continue capturing must do so on the same turn.
Chess in the Third Dimension	Three-D proprietary game from Skor-Mor.
Chess Merels	Lining up three units in a row captures the last enemy unit moved.
Chess with Reserves	Load your units during the game
ChessMate	Cards determine what units you may use.
Chessenat	Game from Columbia with custodial captures.
Chessence	Units move and capture depending on their proximity to their colleagues.
Chessers	Pieces may ride pawns to the end ranks.
Chessgi	Captured units become yours to drop onto the board
Chessky	Dice rolls determine how the units move
Chex	Board is made of cards which must stay connected.
Chimera Chess	Chimeras cannot capture or be captured, but swap positions with the enemy units which they displace
Chinese Chess (Xiangqi)	Number of players is probably comparable to FIDE chess players.
Chitty Chatty Chess	Four-handed game for beginners
Choiss	Build a board from tiles prior to placing units.
Church Chess	Seven bishops
Ciccolini's Chess	Large variant from the early 1800's
Cincinnati Four-Way Chess	Contemporary idea with relatively small central area
Circe Chess	Classic variant in which pieces are returned to their squares of origin if possible.
Circe Progressive Chess	The usual way in which Circe chess is played today.
Circe Vulcanici	Progressive Circe chess, units returning as in the standard non-progressive game, waiting if necessary until the square becomes open.
Circean Chess	Large variant in which pawns evolve into kings.
Circular Chess	Update of Byzantine Chess. At least one club is dedicated to this game.
Citadel	Early 1900's board game.
Citadel Chess	Classic variant of Shatranj.
Cleopatra Chess	No captures, but units attacked by the moving queen are flipped.
Clockwork Orange Chess	Units are returned unable to capture.
Coalition Chess	Alternative setup. No capturing across the midline.
Codrus Chess	Captures are mandatory. Win by forcing the opponent to capture your king.
Cohen's Error Chess	Columbia Cannon Chess, only with Korean style cannons.
Coin Chess	A coin on the board must mirror the moves of a unit, limiting the possibilities.
Colorbound Chess	Checkmate either king with a colorbound army.
Columbia Cannon Chess	Runners must leap one unit to move of capture; knight is 1,0 or 2,0 jumper.
Compact Chess	Small version popular in South Africa.
Confederation Chess	Pieces can merge and separate.
Congo	Successful game invented by a seven-year-old.
Connect Chess	Win by connecting opposite ranks with a chain of mutually supporting units.
Contramatic Chess	You must not check the opposing king, or leave him in check. You may move into check.
Conversion Chess	I chose this one to represent the entire family of co-chess variants.
Coregal Chess	King and Queen(s) are royal.
Coregal Chess 2	King and Queen(s) are royal. Queens may not cross a square under attack.
Corner Chess	Fast-paced variant without pawns.
Corner Chess II	Tony Paletta's modern version of Farmer's Chess.
Corner Rook Skirmish	Except for rooks, all units begin one square forward
Coronation Chess	Bishop and rook can fuse to replace the queen.
Corridor Chess	Setup by Tony Paletta.
Counter Chess	Units may not capture those taller than they are. Win by moving your king to an opposite corner.
Courier Chess	Early German version
Crazyhouse Chess	One-board Bughouse
Creation Chess	Pieces on the far rank may give birth to hybrids.
Creative Chess	Load your own units as you like
Credo Chess	Hexagonal variation commemorating 500 years of English chess publication.
Credo Chess for Three
Cripple Chess	The king may move only to capture.
Cross Chess	Popular in Australia
Crown Chess	Place your own units on the board, starting with the king, then queen, then rooks, etc.
Crush Chess	After every 10 moves, the perimeter disappears.
Cuban Chess	Large version from Havana
Cursed Chess	Squares where you have slain an enemy become uncrossable
Cutthroat ForChess	Four players, each playing alone, on an ordinary board
Cylinder Chess	First and eighth files connect
Dabbabante Chess	2,0 runner need not stop for intervening units
Dark Chess	You can see only the squares to which you could move.
Dark Chess II	As above, but you are protected from moving into, or remaining in, check.
Dead Square Chess	Captures destroy both units, the square, and all neighbors.
Decimal Four-Handed Chess	Fast-moving experimental partnership games by V. R. Parton.
Variant I	Five pawns each
Variant II	Pieces only
Variant III	Two pawns, omnidirectional
Variant IV	Same player cannot take both enemy kings
Defender Pawn Chess	Pawns can move (but not capture) any distance backwards
Defensive Chess	Red cannot move beyond fourth rank. White must checkmate within 50 moves.
Deployment Chess	Place units on markers which disappear if crossed by a friend or occupied by any unit. Won a variants contest.
Desertion Chess	After moving, units recruit adjacent enemies. Winner is the last player able to move.
Detente 007	You move three times in sequence, the middle one being an enemy unit.
Diagonal Quadrant Chess	Different setup and pawn moves
Diamond Chess	Normal set and board, different setup and pawn moves
Diamond Chess II	Diamond-shaped board made up of triangles.
Diana Chess	Miniature chess game from the late 1800's.
Dice Chess I	Move the unit indicated by the roll of a six-sided die. Win by capturing the enemy king.
Dice Chess V	If you cannot move the unit shown on the six-sided die, you lose. First five moves are as in orthochess.
Disguised King I	A secret royal pawn must be protected.
Disguised King II	Win by capturing the secret royal pawn.
Displaced Grid Chess	A Grid Chess variant that allows kings to visit corners, etc.
Dodo Chess	Win by getting your king to the opposite side.
Domination Chess	Win by occupying the center
Double Chess	Move on either of two boards.
Don't Cross Midnight	Chess on a rotating planet; units may not cross the International Date Line
Double Knight Chess I	A second pair of knights replaces the bishops.
Double Knight Chess II	A knight not capturing may move again at once.
Double Move Chess #1	The object is simply to capture the other king.
Double Move Chess #2	Balanced Marsailles Chess. A check or mate ends your turn.
Double Move Chess #3	Bennekom Chess. On each move (except White's first), you move the same unit twice if you can. A check on the first move ends the turn.
Double Trouble Chess	White has only king and bishop but moves twice per turn.
Double Wide Chess	Two adjacent full chessboards.
Dragonfly Chess	Small version with pieces in hand.
Dunsany's Chess	One side has 32 pawns instead of the usual pieces
Duo Chess	Two boards, units moving freely to the corresponding squares
Dutch Billiards Chess	Billiards chess with pocketed pieces returned to their squares of origin.
Dutch Chess	Pawns start on the back ranks and move as queens
Dynamo Chess	Units push and pull one another. Some bugs may remain in the program.
Dynasty Chess	Capture both king and queen, whose moves vary
Earthquake Chess	Center of board runs down a fault.
Echexs	Hexagonal chess for three players.
Echos	Small variant in which you promote and demote your units.
Echo Chess I	If possible, make a second move with a matching unit in the same direction and distance as the first move. It may be a capture if and only if the first move was.
Echo Chess II	If possible, make a second move with a matching unit in the same direction and distance as the first move. The rule on capture is relaxed.
Eclipse Chess	Units in the eclipse zone cannot move or give check.
Edgehog Chess	Queens may move only to or from edges of the board.
Eight Kings Chess	Checkmate any one of them to win.
Emperor Chess	The king may move to, and only to, any square under attack by his forces and not the opponent's.
Emperor of China	Chess-Halma combination with royal king.
English Progressive Chess	In each series, all mobile units must be moved before any unit may be moved again
Enjoyable Hour Chess	Three-Dimensional Chess
Enlarged and Improved Chess	Early large-board variant from Holland
En Passant Chess	All pieces can capture and be captured en passant
Entourage Chess	Any piece (not pawn) adjacent to the king is also royal
Epiphany Chess	Three Kings.
Episcopal Chess	Capture both opposing bishops to win
Erosion Chess	Units erode after eight moves
Escalation Chess	Getting a unit captured lets you move twice on the next turn.
Ethiopian Chess	African variant with distinct mobilization phase
Exchanger Chess	Knights can move to a square occupied by another friendly unit and exchange places with it.
Exotic Pieces	Menagerie of pieces, old and new. Have fun!
Explosion Chess	Whatever units the mover attacks disappear; if the mover is attacked, it also disappears.
Extended Queen's-Side Castling	Restrictions on queenside castling are relaxed.
Extinction Chess	Capture all of any kind of unit. Popular variant.
Falcon Chess	New version completes logical sequence of basic pieces
Fast Track Chess	Pawns may underpromote before they advance to the opposite rank.
Farmer's Chess	Medieval four-sided variant; "Four Seasons Chess"
Feint Chess	Seven of each side's units can check but not capture.
Feudal Chess	Four player game on 9x9
Fianchetto Chess	Bishops and Rooks exchange starting squares.
Fischer Random Chess	Random symmetric starting positions.
Fish Chess I	Pawns can move backwards
Fish Chess II	Pawns can move and capture backwards
Fishaway Chess	Giveaway lumberjack chess.
Five Up Chess	Three-Dimensional Chess
Five Star Chess I	You can also win by getting five of your own units in a new row.
Five Star Chess II	You can also win by completing a row of five units composed from either side.
Five Tigers Chess	Variant of Chinese Chess. Red can make two pawn moves per turn but has no cannons, knights, or rooks.
ForChess	Partnership game on a crowded 8x8 board
Foreign Policy Chess	Peacekeepers are a third army.
Fortresses	Odd shaped board.
Four Player Chess -- Standard	The Verney-Hughes implementation.
Four Player Chess	One of many possible setups. Capture an opponent's king and control the remaining units.
Four Player Chess III	Another popular setup for four players.
Frankfurt Chess	Capturer becomes a unit of the type captured.
Freak Chess	Place your king into a random setup
Free Castling Chess	Liberalized rules on castling.
Free Placement Chess	Choose your own starting position.
Free-For-All Chess	Move either side's units.
French Revolution Chess	Short game with your pawns facing the enemy.
Full Chess	Random symmetric starting positions. Different castling rules from Fischer's proposal.
Fuller's Proposal	Bishops can also move and capture as knights.
Fusion Chess A	Pieces merge and separate
Fusion Chess B	Pieces merge and separate. This time, royalty may cross a square under attack.
GalaChess	Hexagonal variation from 1980.
Gambler's Chess	Mover is determined randomly
German Rules c. 1420
Ghost Chess	The ghosts of captured units reappear.
Glory Chess	A pawn on the seventh rank checks.
Glinski's Hexagonal Chess	The most popular hexagonal variant.
Grand Acedrex	Classic large board setup from medieval Spain.
Grand Chess	Considered among the best of the large-board setups.
Grand Crossing Chess	Win by getting your king to the opposite side.
Grasshopper Chess	Row of grasshoppers behind the pawns.
Grasshopper Chess II	The queen becomes a grasshopper.
Gravity Chess	Moved unit attracts
Gravitational Chess	Major units fall back toward the friendly side
Greater Chess	Large variant from the 1940's
Greek Progressive Chess	You may make one more move per turn than your opponent just did. Not really a Greek regional game.
Grid Chess	Moves and attacks must cross one of the grid lines. Popular variant.
Gridlock Chess	Two-move turns. If after the second move, there are three of your units in a 2x2 area, they are removed. Stalemated players lose.
Gryphon Chess	Units are promoted on each move.
Gryphon Chess II	Units are promoted on each move.
Guard Chess (Variant)	Units guarded by units, other than the king, are immune to attack.
Haigh's Chess	12 x 8 version.
Half Chess	4x8 board, plays well.
Handicap Chess	As in golf, stronger units are given relative limits on who they can capture.
Hawaiian Chess	Pacific Island variant
Hazlewood's Hexagonal Chess	Proprietary game from the 1980's.
Hecatomb Chess	One king and 31 queens on each side
Heraldic Chess I	Heraldic set plus sixteen cards per hand.
Heraldic Chess II	Heraldic set plus ten cards per hand.
Heraldic Chess III	Heraldic set plus six cards per hand.
Heraldic Chess IV	Heraldic set plus two twelve-sided dice.
Heraldic Extinction Chess	Win by capturing any piece plus its pawn
Hermit Chess	A randomly-moving opponent moves more than once per turn.
Hero Chess	The king's pawn is replaced by a unit which mimics the move of any friendly unit on the board.
Hero Chess II	The queen is replaced by the hero.
Hero Chess III	The hero may also move to any square attacked by a friendly non-hero.
Hexachess	Proprietary hexagonal variant
HexChess	Tony Paletta's hexagonal variant.
Hexes	Mike Loyfield's variant on a hexagon-based board.
Hexes Compressed	Another variant.
Hidden Target Chess I	Know which enemy species to eliminate to win, but not which one of yours is vulnerable.
Hidden Target Chess II	Don't know which enemy species to eliminate to win, but do know which one of yours is vulnerable.
Hidden Target Chess III	Double Blind.
Home Base Chess	Captured units return to original squares if unoccupied.
Hopple-Popple Chess	Knights and bishops swap capturing moves.
Hostage Chess	To return one of your captured units, give back an enemy prisoner of equal or greater value. Very good game.
Howell's Chess	Enlarged board with open edge files.
Hunter-Falcon Chess	Two new kinds of runner are added only during the course of the game.
Hurricane Chess	Move as many of your units as you like, once each, each turn. You must escape from check on the first move of your turn.
Hyperspace Chess	Units travelling more than 1 square go through hyperspace.
Hypnotic Chess	If you attack an opposing unit, you may also move it.
Ice Age Chess	Blocks of ice cover the board at intervals
Identific Chess	Place undifferentiated units, then choose who they are after they have moved.
Idle King Chess	Kings do not appear on the board until the 13th turn, and can only move if in check.
Imitating Chess	Units move according to the FIDE move of the last enemy unit
Imitator Chess	A neutral piece must legally imitate your move. It may not capture.
Immobilizer Chess	The immobilizer does not capture, but renders adjacent enemy units unable to move.
Imperial Chess I	Proprietary version for four on a round board.
Imperial Chess II	Proprietary version on a round board.
Imperial Chess III	Proprietary version for four players.
Incognito Chess	The king, a secret piece, and a secret pawn are all royal and must be protected.
Indian Chess	Some local variant rules from the colonial period
Indian/Turkish Grand Chess	Large variant from the 1700's
Insane Chess	Units mutate randomly.
Insane Chess II	Units mutate randomly. This time, you know what the unit will become.
Interregnum Chess	No king or queen; win by promoting a pawn; captured units replaced.
Intrigue Chess	Capturing a particular pawn places the enemy king on the board.
Iron Guard	Non-capturable guard replaces White queen.
Iron Knight	Non-capturable knight
Italian Miniature Chess	5x5 game as played in Italy
Italian Miniature Losing Chess	5x5 losing chess as played in Italy
Italian Miniature Progressive Chess	5x5 progressive game as played in Italy
Italian Progressive Chess	You may only check on your last move of your series. Popular variant.
Janus Chess	Large board variant.
Japanese Chess	Shogi, the extremely popular Japanese variant. I have used conventional symbols, mostly.
Joari-Joara	West Indian variant in which a guarded unit may be captured only if it gives discovered check.
Joust Chess	Two knights. Squares cannot be revisited.
Joyful Chess	One special square enhances a piece's powers, the other diminishes them
Juggernaut Chess	Unstoppable destructive unit moves at random.
Junta Chess	The king and his knights are the junta.
Kamikaze I	Capturing units are removed, except kings
Kamikaze II	Capturing units are removed, kings may not capture
Kamikaze III	If the lone queen checks, she wins.
King and Pawns	White moves twice but has only king and pawns.
King with a Shotgun Chess	Twice each game, a king may shoot down a rank or file
King with a Shotgun Chess II	Twice each game, a king may shoot down a rank, file, or diagonal
Kinglet	Win by capturing all opposing pawns
Kingmaker Chess	The first pawn to reach the opposite rank promotes to the enemy king.
King's Corner Chess	Random setup with kings in opposite corners.
King's Fortress Chess	Random setup with king's in opposite corners and extra pawns in front of them
KnightMate Chess	The knight, not the kings, is royal.
Knight Odds Chess	White starts without the queen's knight.
Knight Relay Chess	Knights confer their movement ability on units they defend. Popular variant.
Knight Supreme Chess	Rooks and Bishops are replaced by Knights in the opening array.
Knightrider Bouncy Chess	Diagonal runners bounce off the walls; knights are knightriders.
Knightrider Bouncy Chess II	As above, but knights cannot capture one another. This helps prevent their early disappearance.
Knights Chess	Rooks, Bishops, and Queens can also move as knights.
Konigsridder	Three attacking players and one defending player.
Korean Chess	Still some bugs in the program.

Korkser Chess	Local rules in parts of Germany.
Korkser Chess II	As above, without initial double pawn moves.
Kriegspiel	Opponent's units are invisible. Very popular.
Kriegspiel Variants
Original Kriegspiel	Know what type of unit was captured.
American Kriegspiel	See where pawn captures possible.
Discreet Kriegspiel	No information on pawn captures or checks.
One-Eye Blind Sighted	Sighted side lacks queen, both knights, and one bishop.
Pickle Pot Blind Sighted	Sighted side lacks both rooks, both knights, and one bishop.
Welbeck Kriegspiel	Place your units as you like.
Mafeking Kriegspiel	Place your units as you like; knights are scouts.
Assassin Kriegspiel	Place your units as you like; knights see adjacent enemies; if you deliver checkmate by any unit except a queen, you lose.

Lambeth Conference Chess	Bishops bouncing off the walls.
Las Vegas Fun Chess	Game with dice, rules by George Koltanowski
Last Rook Chess	King and last remaining rook are both royal
Leandro's Chess	You can move any number of units one time each per turn, providing you do not capture, check, or escape from check.
Legan's Chess	Normal set and board, different setup and pawn moves
Leo Chess	Queen must jump a screen to capture
Levantine Chess	One unit is immune to capture if it is not attacking.
Lias's Proposal	Pawns may move, but not capture, one square sideways.
Lion Chess	Queen, rook and bishops are cannons that must jump to capture. Promotion is to orthochess units.
Loonybird Chess	Christiaan Freeling's small-board game with pieces which capture differently from their normal moves.
Lord of the Rings Chess	Based on the fantasy trilogy.
Los Alamos Chess	Used for the first computer chess program.
Losing Chess	Captures are mandatory, object is to be unable to move.
Losing Chess II	Captures are mandatory, stalemate draws.
Losing Chess III	Captures are mandatory; checkmating or having bare king wins.
Losing Chess IV	Captures are mandatory, being checkmated or having bare king wins.
Losing Sphinx Chess	Losing chess in four dimensions.
Ludus Chessunculus	Small hexagonal variant with single- and double-hoppers.
Lumberjack Chess	Pieces move according to their current file. First check wins.
Machine Gun Chess	Attacked units are removed. The object is to remove all enemy units.
Mad Threeparty Chess	Chess for three. Each opponent has a king which you may check by a move, and one which you must not check by a move.
Madcap Chess	If a capture is available, the player must capture, and continue capturing as long as possible with the same unit.
Madrasi Chess	Units of opposite color and identical kind which attack one another cannot move or give check.
Maelstrom Chess	All 64 squares are initially occupied
Mage Chess	Queen can swap with any friendly unit
Mage Chess II	Queen can swap with any friendly or enemy unit
Magic Carpet Chess	Two teleporting devices.
Magna Carta Chess	White has royal archbishop and royal marshall instead of a king.
Magnet Chess	Moved unit attracts and repels
Maharaja and Sepoys I	Lone king, moving as queen+knight, versus an army
Maharaja and Sepoys II	Lone king, moving as queen+knight, versus an army. The maharaja cannot cross check.
Manchurian Chess	Widely-played regional variant on Chinese Chess
March Hare Chess	Each side moves first a black unit, then a white unit.
Martian Chess	Edgar Rice Burroughs
Maya Chess	Indian variant in which a defended unit (not king or pawn) moves according to the defender(s).
McCooey's Hexagonal Chess	A recognized hexagonal variant.
Meares's Proposal	Bishops can also move and capture one square orthogonally.
Mecklenbeck Chess	Pawns promote on 6th rank
Mecklenburg Chess	Classic 16x8 version for four
Medusa Chess	Non-capturing medusas petrify enemy units
Medusa Chess II	Medusa chess on an 8x8 board
Medusa Chess III	Medusas can also capture
Melee Chess	Large variant, win by entering enemy castle
Melee Chess II	Faster variant
Mercenary Pawn Chess	Use either side's pawns to capture units
Mesmer Chess	If you attack an opposing unit with your mesmerist piece, you may also move it.
Metamorphing Chess	Pieces upgrade when escaping, downgrade when capturing
Metamorpin'-Fusion A	Pieces are likely to proliferate
Metamorpin'-Fusion B	Pieces are likely to proliferate. Here, royalty can cross squares under attack.
Mexican Chess	Large variant from Mexico with 3,1 jumpers.
Mexican King Chess	Win the usual way or by making it safely to Mexico.
Michell's Proposal	Pawns may underpromote on next-to-last rank.
Michelson's Chess	Each side moves first a red unit, then a white unit.
Mideastern Chess	Actually a California variant resembling "Tamurlane" chess
Millennium Chess	8x15 proprietary version with two kings.
Mimic Chess	The mimic may not jump, but may capture a hostile or friendly unit.
Mimikri	Proprietary game from 3M. You know the identities of only one side's units.
Mimikri -- Decoy Game	You know only your own units.
Mimikri -- No! Game	You know only the opposing units.
Mimotaur Chess	Mimotaurs move as queens, may only capture a unit as that unit captures, cannot capture each other.
Minefield Chess	Two of your squares have hidden mines that can destroy an enemy unit when it lands.
Miniature Chess	From an old Martin Gardner column in "Scientific American"
MiniShogi	Japanese 5x5 version
Ministers Chess	Two queens on each side on a 9x9 board, available commercially
Missile Chess	Each unit can rifle-capture once.
Mock Chess	No royal piece, mandatory captures
Modern Chess	Latin American 9x9 version
Modern Chess (Revised)	Latin American 9x9 version. One bishop must begin with a one-square orthogonal move.
Monarch Hexagonal Chess	Proprietary hexagonal variant.
Mongolian Chess	"Shatar", the major form of chess played in Mongolia for centuries
Mongredian Chess	Both bishops on queenside, both knights on kingside.
Monkey Do Chess	If possible, make a second move with any unit in the same direction and distance as the first move.
Variant I	Monkey Done. The second move must be a side-to-side mirror image.
Variant II	Monkey Did. The second move need only be the same distance.
Variant III	Monkey Does. The second move need only be in the same direction.
Monochrome Chess	All units are of the same color. Win by accumulating captures.
Monster Chess	White's normal army faces Red's king and four pawns; Red moves twice per turn
Morley Chess	Large board with the usual pieces.
Moroccan Chess	If you have one or more captures, you must make a capture.
Morton's Chess	Partnership chess for four, with each army vulnerable to attack by only one opponent.
Moscow King Chess	Board starts empty. You place some of your army or move a unit. Kings go on first.
Mountain King Chess	First king to reach the center square of an 11 x 11 board wins
Mouterde's Chess	Board with side extensions.
Move-and-a-Half Chess	Each normal move gives credit for half of a future bonus move.
Mrs. Graycheck's Chess	Pawns promote only to a unit already captured. Kept third-graders' sets intact.
MultiMate Chess	Win by checkmating either side.
Mummy Chess	Kings can move only to castle or escape check.
Mutation Chess (New Zealand Style)	Units other than kings transform into whatever they capture. Queens do not move to give check.
Mysore Chess	Large variant by an 18th century Indian king.
Narrowness Chess	Lots of pawns
Nemesis Chess	New pieces move only toward the enemy king
NeoChess	For four players on an 8x10 board.
NeoSchaak	Load your own units, onto the first two ranks, as you like during the game
Neuter Queen Chess	A non-capturable, non-capturing queen may be moved by either side.
Neutral King Chess	Each side tries to capture the sole king.
New York Twins Chess I	Large board with two kings. Checkmate either one.
New York Twins Chess II	Large board with two kings. Capture one, then checkmate the other.
New Zealand Chess	Knights and rooks swap capturing moves.
Nightrider Chess I	No knights in the usual position; queen is replaced by a nightrider.
Nightrider Chess II	Knights move as nightriders.
Nine Riders Chess	Each piece is a rider
Ninny Chess	Classic board game
No Entry Chess	Bar the opponent's access to one square after each of your moves.
Nommenspiel	Kriegspiel variant where only the squares to which the opponent moves are revealed.
Non-Prise Chess	Only kings and pawns can capture queens, rooks, bishops, or knights
Noris Schach	Popular German proprietary game from the 1970's.
Norwegian Chess	Q/N and B/R transform after each move. Only like units can capture units.
Nuisance Chess	Co-chess variants in which empty cosquares are occupied by neutral units which may be captured but not crossed.
Null Chess	Squares on which captures have taken place can no longer be visited or crossed after they are vacated.
Numericron Chess	Score points by attacking enemy units
Oblong Chess	Ancient 16x4 variant of Shatranj. Several initial setups exist.
Oblong Chess Setup 1 Oblong Chess Setup 2 Oblong Chess Setup 3 Oblong Chess Setup 4 Oblong Chess Setup 5 Oblong Chess Setup 6 Oblong Chess Setup 7
Occupation Chess	Win by occupying an outpost in enemy territory for one move. Pawns promote by capturing, and prisoners can be exchanged and returned to action.
Omega Chess	Commercial large-board variant, plays well.
Outpost Chess	Win by occupying a designated square in enemy territory for one move.
Parachute Chess	Landing units may not attack any opposing unit.
Parallel Worlds Chess	Three Boards. Two have the regular setup, while the third is a twilight zone. Units transfer.
Patrol Chess	A unit may not capture or give check unless it is supported by a friendly unit.
Patt-Schach	Start with an illegal move from a stalemated position.
Patzer Chess	If you can check, you must do so.
Pawn Collector Chess	Pick up counters on the empty squares.
Pawn Massacre Chess	White pieces, but not pawns, swap setup positions with red pieces.
Pawn Odds Chess	White starts without the king's bishop's pawn.
Pawn Progression Chess	Pawns on advanced ranks move differently.
Pawns Game Setup I Setup II Setup III Setup IV Setup V	Tests whether eight somewhat advanced pawns are worth a queen.
Peasant Revolt Chess	Pawns vs. knights.
Perfect Chess	Rook, bishop, knight, plus each of the four compounds ("perfect").
Peruvian Army Chess	A second board has aircraft that can bomb the orthochess board.
Petite Chess	6x5 variant from the 1930's
Philosopher's Chess	Winner of the 40 squares contest
Pin Chess	Pinned pieces do not give check
Plaid Chess	Progressive Grid chess.
Pocket Knight Chess	Drop an extra knight on the board. Popular variant.
Pocket Knight Chess II	Drop the Queen's Knight on the board. Popular variant.
Pocket Knight Chess III	Two pocket knights.
Portuguese Progressive Chess	You can move each unit once at most in a series. Not really a Portuguese regional game.
Power Chess	Seven queens on each side.
Power Chess II	Eight extra pieces
Pre-Chess	Place your first rank as you choose before the game begins
Prisechec	Proprietary game with prison squares
Presto Chess	First check by a unit which cannot be captured wins
Progressive Absorption Chess	Very popular in Italy.
Progressive Fischer Random Chess	Progressive chess with random setups
Progressive Losing Chess	Captures are mandatory; try to lose all your units. Number of moves per turn increases.
Progressive Mutation Chess	Units transform into the kind captured. Number of moves per turn increases.
Progressive Take-All Chess	Very popular in Italy.
Progressive 007 Chess	Move opponent's units alternately with yours.
Promethean Chess	Units visiting the home squares of others leave behind duplicates.
Provocation Chess	Getting checked gets you an extra move. Getting a unit captured gets you an extra move. These can be additive.
Proximity Chess	You must move one of the closest units to the destination of the last opponent's unit.
Push Chess	Capture only by pushing units off the edge. More people play Dynamo Chess nowadays.
Quantum Chess	Move any non-observed unit to any non-observed empty square.
Quatrechess	Score by getting units to the opposite edge.
Queen Odds Chess	White starts without the queen.
Quest Chess	Sides make ten moves in a sequence. Each unit moves a maximum of one time. The opponent gets one move to respond to captures or checks.
QuickChess	Proprietary game from Amerigames.
Setup I
Setup II
Racetrack Chess	Rooks and queens can follow concentric tracks on an expanded board.
Racing Kings Chess	Kings race from Rank 1 to Rank 8
Rainbow Chess	Each side must occupy at least one square of each of six colors.
Rampage Chess	Any unit may move to any square that is guarded.
Random Files Chess I	Move from a random file if you can
Random Files Chess II	Move to or from a random file if you can
Random Pieces Chess	Best of 20 rounds with armies of varying strengths
Ranson's Chess	Classic variant with an amazon which may move only four times.
Rapid Fire Chess	A unit captures all the units it attacks, without moving
Re	Load units, only captures permitted, scored by surviving units.
Re2	No capturing until all units are loaded.
Ready Chess	Take a turn to recharge a unit that has captured.
Recaptureless Chess	A unit which has just captured is itself invulnerable to capture for the move.
Recruiter Chess	Capturer recruits on adjacent squares
Recycle Chess	You may capture your own units and replace them on the board
Red Castle Chess	Red king and QR cannot move except to castle, which wins for Red
Reflex Chess	Force your opponent to checkmate.
Reform Chess I	Load your own units
Reform Chess II	King and Queen Pawns are special
Refusal Chess	You may refuse one enemy move per turn.
Refuse Once Chess	You may refuse one enemy move per game.
Reinforcements Chess	Captured units change sides and are replaced immediately.
Removal Chess	Remove an enemy knight after move 6, a bishop after move 12, etc.
Renezans Chess	Proprietary game, 9x9, in which the occupant of the center square can move as any piece.
Repatriation Chess	Pairs of captured units are returned to the board.
Reserve Chess	Units may be removed from the board and dropped back in later.
Rettah Chess	King can move as any piece but must capture its attacker.
Revelation Chess	The object is to obtain four knights of your color on the board.
Reverso Chess	White king and queen are reversed in the initial position.
Richard Goode's 3D Chess	Three-Dimensional Chess
Rifle Chess	Units capture without moving
Riga Chess	Escort King and Queen to the opposite side of the board. Not really a regional variant.
Riley's Four Army Chess	Several ways to win.
Rolling Kings Chess	Kings move by themselves.
Roman Chess	10x10 variant available commercially
Romanchenko's Chess	New chessboard with sides displaced
Rook Odds Chess	White starts without the queen's rook.
Rook Square Chess	Enemy rook squares are royal
Rotary Chess	Christian Freeling's game, offered as a development of "Ploy".
Rotation Chess	Every ten turns, you switch and play the other player's units.
Round Chess III	Queens and rooks may move around concentric tracks.
Royal Stables	Seven Knights
Rubble Chess	Clear squares by moving.
Russian Fortress Chess	Old four-handed chess game, with a considerable following in pre-communist Russia as well as elsewhere.
Russian Progressive Chess	End odd turns by moving an enemy unit
Russian Stacking Chess	Revival of a classic Russian variant. Stack units rather than capturing.
Russian Symmetric Chess	Russian 9x9 variant. Each bishop can make one orthogonal king's move.
Rutland's Chess	14x10 version
Schachdame Chess	Pawns, a bishop, and a royal queen.
(Paul) Schooling's Chess	Units transform when they capture
Scorpion King Chess	King can also move as grasshopper
Scotch Chess	Number of moves increases each turn. Popular variant.
Scotch Modern Chess	A check or move to a guarded square ends the series. Not really a Scotch regional game.
Secret Agent Chess	You may take control of a predesignated opposing minor piece.
Secret Service Chess	If the king in in check, a secret service agent must exchange places with him if possible.
Self Eliminator	You may capture your own units
Sentinel Chess	The sentinel becomes a secondary army of up to eight pawns.
Seven Knights Chess	Unusual army for Red
Shafran's Hexagonal Chess	A classic hexagonal variant from Russia.
Shakti	Christiaan Freeling's simple, elegant game with disappearing squares.
Shatranj	Arabian chess, ancestral to the Western forms.
Shoot Chess	Rifle chess with mandatory captures.
Shrapnel Chess	Nearest units at 45 degree angles from line of capture are also destroyed.
Shrink Chess	Emptied rows and columns vanish permanently
Shrink Chess II	Emptied edge rows and edge columns vanish permanently
Shuffle Chess 1	Normal sets, king and rooks on their usual squares, white and black need not match, bishops balance
Shuffle Chess 2	Normal sets, randomly placed, no castling, white and black match, bishops need not balance
Shuffle Chess 3	Random units, white and black match, no castling, bishops need not balance.
Shuffle Chess 4	Random pieces, bishops (if any) balance, white and black need not match, no castling.
Siberian Chess	Very nice chess variant with jump captures, from Altai in Siberia.
Skirmish Chess	Armies start one rank forward each.
Slater's Chess	Fast four-player game using the standard board.
Slippery Center Chess	Units slide over the center squares.
Sniper Chess	Rooks, bishops, and knights do not capture as they move.
Snowplow Chess	Rooks, bishops, and queens may continue moving in the same direction after they capture.
Soccer Chess	Kick the ball into the enemy goal.
Spanish Rules 1283
Spanish Rules 1500
Speed Game	6x5 variant from Holland
Sphinx Chess	Four dimensions.
Split Board Chess	Swap halves of the board every 5 moves
Sputnik Chess	Rooks, bishops, and knights on the enemy half of the board get free moves.
Standoff Chess	A check only works if it could be carried out by the defender without the attacker then being in check.
Start-Again Chess I	Each unit may return to its original square if unoccupied.
Start-Again Chess II	Each unit may return to its original square if unoccupied, or (unless it is a pawn) the starting square of its enemy counterpart.
Static Chess	Take turns placing a unit so that none attacks another.
Stealth Chess	You must guess which opponent unit is which.
StereoSchach	One of the most popular 3D chess games.
Stochastic Chess	Place or move squares in addition to units.
Stratomic Chess	Tactical nuclear missiles may be deployed after a piece is captured in the ordinary way.
Strip Chess I	Remove an article of clothing each time you are checked. Rated PG-13.
Strip Chess II	Remove or replace articles of clothing as units are captured. Rated PG-13.
Strong Pawns Chess	Pawns move and promote as minor versions of the pieces they represent.
Sudden Death Chess	If you do not capture, you must remove one of your own units.
Super Chess I	Big proprietary game for four. Pawns meet their opponents as in orthochess.
Super Chess II	Proprietary game from the 1970's.
Super Chess III	Big proprietary game with archers and cyclopses.
Super King	King moves as queen but cannot move across a square under attack
Super Knights	If a knight does not check on its first move, it may make a second move during a turn.
Swarm Chess	Each of your units must move each turn if possible.
Swap Chess I	Friendly units may swap places
Symmetry Breaking Chess	Units become defined as they are selected and moved
Synchronous Chess	The two sides truly move simultaneously.
Syrian Chess 1850
Tag Chess	Units which attack the mover are captured
Take Me Chess	You may require that your last-moved unit be captured by a particular opposing unit, when possible. Object is to lose your units and be unable to move.
Tamerlane Chess	Old Persian large-board game, widely-played in medieval times
Tandem Chess	Bughouse variant where both boards score and a dropped unit may not give check.
Tank Chess	Tanks, bombs, and nukes. My favorite.
Tank Chess II	Only the Queen's Rook is a tank.
Taurus Free-For-All Chess	Chess for four, no partners.
Taurus Three-Way Chess	Chess for three on a four-way board.
Taurus Two-Team Chess	Chess for four, with partners.
Teamster Chess	Pawns pull the friendly piece behind them.
Tedco Chess	Three-Dimensional Chess
Teleport Chess	Each piece (not king or pawn) may teleport once to any vacant square.
Termination Chess	Each side must move once with a piece and once with a pawn each turn.
Tesche Chess for Three	Survivor wins.
Thai Chess	Usual variant played in Thailand
Three Check Chess	If you deliver check for the third time, you win.
Three-Dimensional Chess	5 x 5 x 5 board, the most popular of the 3D variants
Tibetan Chess	Non-royal black capturers assume the identities of the captured white units. No relationship to real Tibetan culture.
Tiger Hunt	White army, complete except for its queen, against a lone Q+Kt
Tile Chess	Popular chess game with tiles which must remain connected.
Tim's 3D Chess With Super Pawns	Two kings on each side Super-pawns move, but do not capture, straight forward, up, down, or sideways.
Toilet Roll Chess	Disguise your units. If challenged, they must be revealed. If it moved illegally, the move must be withdrawn. If it moved legally, challenger forfeits the move.
Too Many Bishops	Place an enemy bishop after your own move
Toystore Chess	Five pieces, no pawns.
Transcendent Chess	Random ordering of first ranks.
TransChess	CoChess variant. You must move any non-royal unit on a cosquare to an empty square of your choosing.
Transpose Chess	Sideways board, promote your pawns quickly
Trap Door Chess	Once moved, a unit disappears if it is not moved again within 5 moves
Trap Door Chess II	Two boards, with trap doors and mattresses
Triangular Chess	George Dekle Sr., 1986.
Triangular Chess I	Rooks and bishops run in only three directions.
Triangular Chess II	Runners have more extended movements.
TriC	Chess for three on a hexagonal board. Large proprietary game.
TriChezz	Chess for three on a circular board. Classic proprietary game.
Trigon Chess	Chess for three on a board of triangles. Modern proprietary game.
Triplet Chess	Each turn, move a king, a pawn, and another piece; win when opponent cannot
Triscacia	Chess for three.
Triscacia II	Chess for three on a 10 x 10 board.
Tritabul	Progressive chess in three boards. Units may transfer.
Troy	Hexagonal variant from a Dutch game club.
Tsunami Chess	Variant of Avalanche Chess, pawns move toward your side
Tula Chess	Russian local variant
Turncoat Chess	Random units turn traitor.
Turnstyle Chess	Four player variant. Each team member controls half the board.
Tutti Frutti Chess	Eight different pieces.
Twenty Knights Chess	Red's 20 knights must mate White within 50 moves.
Twenty-First Century Chess	George Jelliss's elaborate game with runners and hoppers.
TwiKnight Chess	Once per game, you can move a single knight twice.
Twilight Chess	Win by mate, stalemate, taking all pawns, taking all rooks and queens, or taking all bishops and knights.
Twin Chess	Two of each kind of piece.
Twin Chess II	Two of each kind of piece. Another setup.
Twinkle Chess	Alternately remove and replace an enemy pawn after each move.
Twinkle Chess II	Remove and replace enemy pawns.
Twin Orthodox	Two kings on a 10x10 board.
Twins Chess	Units of a kind move and are captured together.
Variant 1	1. King and queen are twins
Variant 2	2. Twin queens both start on same square
Variant 3	3. Twin queens only
Variant 4	4. Twins can occupy the same space
Variant 5	5. Move separately, captured together
Variant 6	6. Move together, captured separately
Variant 7	7. A piece and its pawn move together
Variant 8	8. A piece and its pawn are captured together
Variant 9	9. A piece and its pawn move and are captured together.
Two Fisted Chess	Double-move chess. You must move different pieces of the same kind. King and queen are of the same kind. No penalty if you cannot make the second move.
Two Kings Chess	Win by checkmating either one.
Ultima Chess	Popular game using the same units, with one rook upside-down
Unachess	Add your units when and where you choose.
Unachess II	Landing units may not check.
Uncertainty Chess	Omnidirectional pawns promote at will to the pieces.
Union Chess	Pieces can fuse into stronger units.
Unirexal Chess	Which player can win faster, given a queen in place of a king?
Upside Down Chess	Based on promoting pawns
UrChess	Some likely primitive features are restored
Valdskak	Icelandic version. Supported units cannot be captured.
Verney's Four-Handed Chess	The original popular four-handed version
Viennese Chess	Free placement with a screen
Warp Chess	Ranks 3 and 6 mirror each other, as do 4 and 5.
Warlord Chess	Knights move as gryphons; queens move as gryphons or bishops
Wellisch's Hexagonal Chess	Hexagonal chess for three players.
Welschen Schach	Unusual setup and promotion rules.
Wild Chess 7	King and three pawns.
Wild Chess 8	Leads to an open position.
Wild Chess 9	Royalty passes between the king and his guard
Wildebeest Chess	Game with several kinds of jumpers; one of the more-often played large-board variants.
Wolf Chess	Older European game with unusual pieces.
Xenophobic Chess	Win by penetrating enemy territory
Xadrez Rex	Hexagonal variant from Brazil.
Yeoman Chess	Pawns can move diagonally backwards and capture straight back
Zen Chess	Capture enemy units according to their moves. Checkmate king as usual.
Zip Chess	Pawns may move any number of square forward.
Zombie Co-Chess	Co-Chess variant
Zoo Chess	Capture four kinds of opposing units