Shrink Chess

There are many, many variants of chess. Some variants just add other rules, others involve new pieces and there are some which need to be played on a board with a different shape. Most of these variants are not great to play, maybe fun for a few times. ‘Shrink Chess’ is one of the more interesting variants, which I kept playing for a least a couple of years. In this variant the board size changes, shrinks during the game. The game was called ‘Krimpschaak’ in Dutch, which is perhaps more accurately translated as ‘Shrinking Chess’. In any way the name of the game was not intended to bring up any association to ‘psychiatrists’, although it’s a weird game 😉

Rules of the game

(taken from the to which I mailed the rules of Shrink Chess back in 1996! )

The game starts on a normal chessboard, with the usual opening setup. When a player moves a piece and thus doing so empties a row or column on the board, the board shrinks. This means that this empty row or column disappears from the board. In practice, this means that all pieces on one side of the line are moved one square in the direction of the line, and the last line (horizontal or vertical) now is no longer used. During the game, the board can only decrease in size – rows or columns never come back. It is easiest (for writing down the moves of the game, and remembering which lines are in play) to always shrink in the direction of a1.

A move may only be made when the position after the possible shrink is legal. For instance, it is not allowed to move such that your king is in check after the shrink due to your move.

Some additional rules:

  • Long or short castling is only allowed when there are two or three squares between the king and the rook. For instance, when the d-column has disappeared, short castling on the queens side is allowed. (All usual requirements for castling also must be fulfilled.)
  • A double first step with a pawn (like e2-e4) is only allowed when there are still 8 rows on the board.
  • A player that causes a pawn to promote, decides which piece it is turned into. (This can possibly be the player not owning the pawn: e.g., when black has a pawn on a2, and white moves the only piece on the a-line to a square on another horizontal line, then the black pawn on a2 promotes: white can decide to which type of piece.)

Some examples

A simple example shows that even the smallest bord sizes can occur in real games.  We start on a 3 x3 board in a position in which White has a decisive material advantage.

White to move and mate. White plays 1.Rb2-c2+! (Rb2-b3 is similar)

It looks White is just giving up his last piece!? But this is Shrink Chess!

The b-file has just been emptied, it has to disappear.

Position after move 1. The Rook is well protected.

Black had only one move left 1… Kb3-a3

Only move for White as well: 2.Rb2-a2+

The b-file was emptied by White’s last move

And finally we end up with the smallest board possible:


Now a full game

1.e2 – e4, d7 – d5 a Scandinavian? 2.e4 x d5 and the board shrinks (the fourth row has been emptied). It’s easiest for notation to use the fieldnames before the shrink. 2… c6 – c5 3.d4 x c5 shrink again! 3… Nb6 x c4 The position is now as follows:

Position after 3… Nb6 x c4

4.d2 – d3, Nc4 – e3!? a sacrifice, the position is getting more cramped after the shrink. Next diagram:

Black sacrifices for a shrink


5.f2 x e3, Bc5 x e3 6.Bc1 x e3, f4 x e3 7.d3 x e4, Qd5 x d1+ 8.Ke1 x d1, Bf5 x e4 9.Kd1 – e1 next shrink 9… Bd4 x f2 10.Be1 x f2, (shrink) d3 x e2+ (shrink! third row emptied, pawn on e2 is protected) 11.Kd1-c1, Kd4-c4+ (shrink, but not a good move) 12.Nb1 x d2+, e3 x d2+ 13.Kc1 x d2 and now black seems to be in trouble

Position after 13.Kc1 x d2

13… Re4 x e2+ 14.Re1 x e2, d3 x e2 15.Nd1 – e3+, Kc1 – b1 16.c2-c3++ checkmate!


A little history of Shrink Chess

When I studied Mathematics at the Radboud University Nijmegen in the 1990’s, I used to play many games with my fellow students at the canteen of Mathematical students association DESDA. Among those games were also a couple of chess variants. Shrink Chess had already been played at DESDA before I started my studies in 1990, but I think it was only a recent innovation. The origins I could trace back to a sister association from the VU University Amsterdam, STORM. There hade been exchange visits between STORM and DESDA in early 1990 or 1989. And I guess the Nijmegen students picked up the rules during that exchange.
Later I found an article in a magazine of STORM (from 1989 or 1990?) which gives a brief description of the rules. But those were not very clear and did not handle castling and en passant rules. The additional ruels as described above were my contribution to the game, although they came up during gameplay and therefore my opponents should deserve some credit for them as well 😉 Especially the promotion rule was something which I was very happy with. It’s quite an unique rule in all chess variants, in which the opponent can decide to which piece a pawn promotes when he makes it appear on the last row by shrinking that last row away from the board.

When I stumbled upon the website some years later, I wrote the website owner, Hans Bodlaender, a mail with the rules. I think I wrote them in Dutch and Bodlaender made the translation. He might therefore very well be the actual name giver to the game in English.


  • I used to play openings that were intended to prevent too many early shrinks e.g. 1. g3 and 2.h4. This way it was possible to use much of my normal chess reflexes in the opening fase of the game. These anti-shrink openings were appropriately named after laundry products like “Persil” and “Witte Reus”.

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