Check out Alice Chess, our featured variant for June, 2024.

This page is written by the game's inventor, Gary Gifford.

Dimension X

This game consists of two parallel planes of existence. On one plane we have a typical chessboard; on the other plane (Dimension X) we have a board inhabited by strange trans-dimensional chess pieces in the form of snakes, spiders and crabs. These creatures can leave Dimension X, and also return to it. The normal chess pieces cannot go to Dimension X. Normal chess pieces can capture Dimension X pieces, if they [the normal piece] are not "stuck" by an enemy Spider. O V E R V I E W O F W H A T M A K E S A T U R N These 4 moves can be made in any order. Only move # 1 is mandatory. On each turn a player: 1. Must make a normal move with a FIDE piece (unless he can capture the enemy King on that very turn… only in this case is this part of a turn not required). 2. Can move his Crab [to or from Dimension X; or within Dimension X] – or make a “pinch” 3. Can move his Spitting Cobra [to or from Dimension X; or within Dimension X] – or make a “strike” 4. Can move a Spider [to or from Dimension X; or within Dimension X].


As in figure.  

Note the central zones for each board, also note the following terms:

Dimension X board,  a parallel universe board inhabited by trans-dimensional pieces.

While in Dimension X, trans-dimensional pieces never attack each other.  

See notes for board/piece tips.


A) On the Real World Board (FIDE Board): Pieces are as in Chess
   Pawns will only promote to "real world" pieces (Q, R, N, or B).

B) Dimension X: Crab, Spider, Spitting Cobra


Object of the game: capture your opponent’s King. Or, make it such that he cannot move a FIDE piece on his turn. IF a "NORMAL MOVE" CANNOT BE DONE, THE IMMOBILIZED PLAYER LOSES UNLESS HE CAN CAPTURE Your KING. H O W T O P L A Y Perform 1 or more of the following moves, in any order. MOVE 1 MUST BE PERFORMED unless you capture the enemy King on your turn. The other 3 moves or actions (or up to 3 trans-dimensional pieces) are optional. 1. Move a FIDE Chess Piece. This is as in chess, except a King may move into or be exposed to check. This is typically only done when absolutely necessary, or when doing so will be followed up by a capture of the opponent’s King via a trans-dimensional piece action. There is no Checkmate or Stalemate in this game. Win by capturing the opponent’s King. FIDE pieces cannot move into Dimension X. FIDE pieces CAN CAPTURE Dimension X pieces. 2. Move or perform an action with 1, 2, or 3 Trans-dimensional pieces. MOVEMENT of TRANS-DIMENSIONALS + Movement from Dimension X to FIDE Board, or visa versa. --- From one square to its associated square on the other board. For example: B2 to b2. C3 to c3. d4 to D4. On the FIDE board only, Edge flanks and files are OFF-LIMITS to these pieces. + Movement within Dimension X.--- Free reign of movement within Dimension X. Other than blocking a piece, trans-dimensional pieces has NO EFFECT on another WHILE IN DIMENSION X. Spider and Crab – Like a King (1 space). Spitting Cobra – Like a King, but 1 or 2 spaces. Dimension X pieces can move off of [or on to] the Fide Board. They can never move while on the Fide Board, that is from one square to another. Trans-dimensional pieces can never appear on the FIDE Board's outer edge Files or Ranks. (see following diagram). NOTE: THE OFF_LIMITS IS TO OCCUPANCY, NOT TO ACTION (SUCH AS WEB EFFECT, COBRA STRIKE, OR CRAB PINCH). A C T I O N S o f T R A N S D I M E N S I O N A L S These actions can be repeated on each turn, on the FIDE board only. ====================================================== **** S P I D E R S **** Web Action - Spiders automatically immobilize all adjacent enemy pieces (including an adjacent enemy Crab and an adjacent enemy Cobra) with their ultra-powerful webs. Enemy pieces in a web remain immobilized until such a time that the capturing Spider either returns to Dimension X or is captured. Spiders have no effect on other Spiders. COMMENTS: Pinch / Web combo. A piece which is pinched, while in a web, is removed from the board. If stuck in a web, a Crab cannot pinch. If stuck in a web, a Cobra cannot spit (cannot strike). ==================================================== ++++++++++++++++++++++++++++++++++++++++++++++++++++ **** S P I T T I N G C O B R A S **** Spitting Cobra Strike – When a “Strike” is performed the player making the “strike” removes the opponent’s stricken piece, or pawn, or King from the board (that last case wins). The target piece of the strike must be no further than 2 orthogonal or diagonal spaces from the Cobra at the time of the strike. !!! Note that on the normal (FIDE) board, Trans-dimensional pieces CAN BE VICTIMS OF A STRIKE and therefore removed from the game. COMMENTS: If stuck in a web, a Cobra cannot spit (cannot strike). +++++++++++++++++++++++++++++++++++++++++++++++++++ &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& **** C R A B S **** Crab Pinch – When a “Pinch” is performed the player making the “pinch” relocates the opponent’s pinched piece or pawn or King (this piece must be adjacent to the Crab at the time of the pinch) to a square of the pinching player’s choosing on that opponent’s first rank. !!! When a Black Crab Pinches a White Piece (or Pawn) --- the White Piece or Pawn gets relocated to a space in the a1 to h1 rank. The player who does the pinching chooses the vacant space !!! When a White Crab Pinches a Black Piece (or Pawn) --- the Black Piece or Pawn gets relocated to a space in the a8 to h8 rank. The player who does the pinching chooses the vacant space. In the above two cases; if that rank is completely occupied, then the pinched piece is removed from play. ALSO - If the piece being pinched is already on the first rank, then in that case if the 7 other spaces are occupied the piece is removed from play. (Even if it is the King). !!!! Trans-dimensional pieces can be pinched while on the normal (FIDE) board. If a trans-dimensional piece is pinched, it is removed from the game (even if it is not in a web). COMMENTS: Pinch / Web combo. A piece which is pinched, while in a web, is removed from the board. If stuck in a web, a Crab cannot pinch. Pawns can end up on a player’s first rank due to the pinching action. &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& -------------------------------------------------------------- D I M E N S I O N X P R O B L E M S - Removed (see Note) (Solutions appear in the Notes section) Note: Problems # 1 through #7 have been removed due to bandwidth issues. I will e-mail problems 1 through 6 to those who want to solve them or who want to see the problems. Problem 7 I noticed under "What's New" on July 4th. You can move pieces around... Problems 1 through 6 are being added in text format. Completion: TBD. Problem Solvers (Problem #1): Thomas J. McElmurry, Fergus Duniho, Jianying Ji, Jeremy Good. PROBLEM 1: / = Space; C= Crab; S = Snake(Cobra) A = Spider (arachnid) Upper Case = White; Lower Case = Black Fide Board Setup. Left to right. Row 8 at top. Row 8: //bq/k// Row 7: ppp/C//p Row 6: ///n//Ar Row 5: /n//////B Row 4: ///PSP// Row 3: //P/Na// Row 2: P/Ps/KPP Row 1: //////// Dimension X: Empty except for 1 black crab on A4. Intro to Problem 1: Black has just completed his turn by moving a Spitting Cobra (s) and Spider (a) from Dimension X to the Fide board. Black threatens spitting deadly venom onto the imobile White King. What should White do? Solution is in the Notes section. Note: Problem Solvers are those who have provided the correct solution to a problem prior to the posting of the solution in the Comments section. Problem 2 - the following link will take you to the problem. You can cut and paste the link to get it to work. /play/pbm/play.php?game%3DDimension+X+Problem+2%26settings%3DDimension+X&submit=Move Problem Solvers (Problem #2): Thomas J. McElmurry, Fergus Duniho, Jianying Ji, Jeremy Good. Problem Solvers (Problem #3): Thomas J. McElmurry, Fergus Duniho, Jianying Ji. Problem Solvers (Problem # 4): Thomas J. McElmurry, Fergus Duniho, Jianying Ji Problem Solvers (Problem # 5): Thomas J. McElmurry, Jianying Ji, Fergus Duniho Problem Solvers (Problem #6) Fergus Duniho, Thomas J. McElmurry, Jianying Ji Problem # 7: Appeared under CV's "What's New" week of July 4th. Problem Solvers (Problem #7) Thomas J. McElmurry The Position is: FIDE BOARD: Black King on c3; White King on h3; White Pawn on g5 DX BOARD: Black Spider on D3; Black Crab on E6; White Spider on G3 Problem: After white plays his Pawn on g5 to g6 it will be black's turn. Who should win this endgame? Or, is it a draw? Setup link to preset is below (setup).


Q: If neither player can make a "normal Fide piece move" is the game declared a draw?
A: No.  In the scenario you speak of the player whose turn it is to move would lose, unless he could capture his opponent's King on that turn.

Primary Source of inspiration: Alice Chess and a game of Blue Chip Chess with Jeremy Good.

A special thanks to Jeremy Gabriel Good for creating the Dimension X pre-set.

A special thanks to David Howe for his Alfaerie Variant Chess Graphics (based on Eric Bentzen's Chess Alpha font).

A special thanks to Fergus Duniho for discussing some difficulties with the layout of the original rules with me, prompting me to better arrange them on June 20, 2006 (which I did).

A special thanks to Thomas J. McElmurry for taking time to write relatively detailed commentary regarding the 5 Problems.  

And a special thanks to for hosting and archiving chess variants.



If you will be playing in-person with friends, or you want to keep a board set up for an e-mail game, then I recommend the following (but feel free to change the steps you don't like):

1) Use just 1 board and standard piece set.
2) Use 3 checkers per side (or paper, cardboard circles) to make a Crab, Spider, and Cobra 
3) put them on your board and put the normal pieces on top of them as applicable to the starting setup.
4) Make all your moves on the single board.  The graphic-checkers indicate that the piece is in Dimension X... You will always know instantly where it can surface.
5) Off to the sides of the board have 3D figurines for Crab, Spider, Cobra. Realistic figures are nice, but-- if you have locking checkers you can simply put your graphic-checker on top of 3-checkers to indicate when it is "on" the real board (i.e.) that it has left Dimension X. 

The main idea here is that it will be easier to play the game using one board than it will be using 2 as in the computer version. 

6) For the very serious player, mark off the central Zone with marker, thin strips of duct tape, gluing lines of yarn, or some other means.  Of course, I'd only do this to one of those cheap cardboard boards.  I often see plastic piece sets with boards for under $5 U.S.


S O L U T I O N S   T O   D I M E N S I O N   X   P R O B L E M S 

Problems composed by Gary K. Gifford 
Solution annotations by Thomas J. McElmurry

     Annotated by Thomas J. McElmurry

I came across the game . . . and had to stare at the problem for some time.  I was nearly convinced that it was impossible, but also nearly convinced that you wouldn't have posted a problem without a solution.

Of course the solution becomes obvious once you see it . . . 

White must: pinch the black King, moving it to e8; transfer the Spider to the Dimension X board, clearing a path for the Bishop; and move the Bishop to e8, capturing the King.

The Spider and Crab can act in either order, but since the resulting position is the same, I think it makes sense to consider these two permutations as being the same move by White.  With this definition, the solution is unique (since the white Cobra is trapped in a web) – a nice touch.  All in all, an excellent problem.


     by Thomas J. McElmurry

Well, this is getting fun.

The second Dimension X problem has multiple solutions; in fact I count 
24 [although 23 of them are essentially the same].  In any case White must first get rid of the black Spider on g6.  There is only one way to do this:

* The white Spider transfers to F5 on the Dimension X board.
* The white Spitting Cobra strikes the black Spider.

Then White has two options.

* The white Crab pinches the black King, moving it to a8.
* The white Rook captures the black King on a8.

* The white Crab does something, or not.
* The white Knight captures the black King on h7.

Note that in the second case, the white Crab's action is not necessary for the capture of the black King.


     by Thomas J. McElmurry

I think problem 3 is the best one yet.  Black is in quite a pickle, but he can get out of it and win, as long as he can remember not to panic and to deal with the threats one at a time.

Black plays K g6xg7; Cobra G6-g6; Spider E3-e3, and the black King is safe. The Queen has been captured, the white Cobra's strike is blocked by the black Cobra, and the white Bishop is immobilized by the black Spider.

In fact the Spider's web has ensnared all three of White's normal pieces. The only white piece free to move is the Cobra, which must free its comrades or capture the black King if White is to survive.  It is within striking range of both the black King and the black Spider, but it is blocked by its black counterpart in the one case and by its own Pawn in the other. The black King survives, and White is unable to move a normal piece.  Black is victorious for the first time in these problems.


     by Thomas J. McElmurry

Of course White can play Spider C2-c2, immobilizing both attackers.  As long as he doesn't also play Kxb3 (which would put his King right back into danger), this is sufficient to avoid the immediate capture of his King.  But White has been around the game long enough (this is his fourth problem, after all) to know that no Dimension X position is truly safe, so he needs to launch a counterattack.

White plays Spider C2-c2; Cobra F4-f4; f8=N, delivering a Dimension X [Game] checkmate.  The black King is attacked by the newly Knighted Pawn, which cannot be captured by any black piece (nor can it be pinched or immobilized, as Black has lost his Crab and Spider).  The King has no escape squares:

g7 is attacked by the white Bishop, h6 by the white Cobra, and g6 by 
both white Knights.  Black's only hope, then, is to capture the white King immediately.  (There are too many white pieces on the board for that trick from problem 3 to work again.)  The black Knight on e1 can capture the troublesome Spider, but even then the white King is safe: the Cobra's attack is blocked by the Knight on c2, and the black Queen cannot move because Black has already moved a normal piece.

Black cannot win immediately, and he cannot protect his King.  White is sure to win on the next move.

Great problem!  For the first time, the solution takes two moves.  And under promotion is always fun.  Also, the possibility of Rxe1 (to preserve the white Spider) had me barking up the wrong tree for a while.


     by Thomas J. McElmurry

One of the great things about these problems is that instead of stating
"Black to play and win in 2", you ask "Can Black win in this position?"
This means that the whole time I'm struggling to find the solution, this little voice in the back of my mind is saying "Maybe there isn't one." But you wouldn't do that to us, would you?  This time I was starting to think you had.

In fact you hadn't, but then you knew that.

Black can't capture the white King on the first move, so he must deal with the threats to his own King.  The white Knight on g6 can only be captured by the black Cobra, but the white Cobra can be captured either by the black Knight or by the black Bishop on h6.  For quite a while I wanted to capture with the Bishop, in order to use the Knight on the next move to capture the white Spider and free the black Queen and Rook.  But then those pieces wouldn't be able to go after the white King until Black's third move.  By that time, White would have played Qf7, and the black King would fall first.  So Black needs a faster plan.

Black's first move is: 1... Cobra strikes Knight; Knight takes Cobra; Crab G3-g3, threatening to annihilate the white King via the Pinch/Web Combo (which I had almost forgotten about).

Now White cannot capture the Black King immediately, and the only 
Defense against the Pinch/Web threat is to capture the black Spider with the d5-Bishop.  (The optional addition of Spider c7-C7 is useless for White.)

If White plays any other move, then Black wins by Pinch/Web Combo.

If White plays 2. Bishop takes Spider [with or without Spider c7-C7],
then Black plays 2... Crab pinches King to c1; Cobra g5-G5; Bishop takes King.  And Black wins in two moves!

     by Thomas J. McElmurry

The Black King is probably feeling rather nervous about now.  He has no
defenders nearby, and with the White Knight stationed on c6 it will 
take him three moves to get out from behind his immobilized Pawns.  He'll be dead by then unless Black can find some counterplay.

With his King too terrified to move and all his pawns immobilized or
blocked, Black looks to his Crab, Cobra, and Knight.  He plays Crab 
G6-g6 (threatening to pinch the white King); Cobra C3-c3 (attacking three 
squares on the first rank); Knight c2-e1 (protecting the Crab).

The White King will fall on the next move, either to the Cobra after
being pinched to a1 or c1, or to the Knight after capturing the Crab.
Perhaps he will choose the latter, deeming it more honorable to be 
slain by a valiant foe on the field of battle than to be spat upon by a vile serpent.

     by Thomas J. McElmurry

[Black} can deal with the white Pawn easily enough, capturing it in three 
moves if it runs or four if it doesn't.  This will leave Black with a 
material advantage of King + Spider + Crab vs. King + Spider.

While pondering this problem, I considered some simpler cases, and 
learned that King + Spider wins easily against a bare King.  But it seems that the Spider can also be a strong defensive piece.  

In the present case, White can simply station his Spider on g2 and move his King around on g1, h1, and h2.  With no long-range black pieces remaining, the white Spider is immune from capture, cannot be forced to move, and prevents the Black King and Crab from infiltrating the corner.  Meanwhile the Black Spider can keep the white King away from h2 by moving to G3, or from g1 by moving to F2.  But at any given moment, either g1 or h2 is safe for the White King, and h1 is always safe, because the black Spider cannot reach the edge squares on the FIDE board and g2 is occupied by the White Spider. The White King always has a safe move, and the game is drawn.

*Note this problem tricked the composer who thought Black had a forced win.  But Black only wins if White plays poorly.  The drawing technique of King + Spider + Crab versus King + Spider is good to know.


I dedicate this game to the memory of H. P. Lovecraft, who wrote many stories of other dimensions and to the memory of Lewis Balog, a friend and member of the Theosophical Society.  Lewis loved to discuss theories of time distortions and other dimensions.  He passed away several years ago of a serious illness.  When I last saw Lewis in good health he looked a lot like "Skipper" from the TV show Gilligan's Island.  Lewis was about as good-spirited as the Skipper character. - gkg

Dimension X - (c) Gary K. Gifford, June 2006

This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.

By Gary K. Gifford.
Web page created: 2006-06-11. Web page last updated: 2006-06-11