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Cheapmate Chess

A humble variant

Invented by Robert Price

I got the idea for this variant while I was reading the FIDE Handbook for the first time. Most chess variants are made by adding some additional rules, or modifying existing ones. This variant results from the deletion of a rule, or at least part of one.

To quote article 5.1.a of the FIDE Handbook effective July 1, 1997:

  • "The game is won by the player who has checkmated his opponent's king. This immediately ends the game, provided that the move producing the checkmate position was a legal move. [Emphasis mine]"
The italicized portion is necessary because, ordinarily, an illegal move is allowed to stand if its illegality is not noticed before the end of the game, so an illegal move resulting in checkmate would otherwise not have a chance to be declared illegal.

In Cheapmate Chess, all FIDE Chess rules apply except for that italicized section. Thus it is possible to achieve checkmate by means of an illegal move. I call this situation cheapmate.

Now, I don't want to allow the movement of multiple pieces, or the reintroduction of pieces that have already been captured, so here are the rules governing the FIDE-illegal move:

  • The active player moves exactly one of his own pieces from any position on the board to any position that is empty or occupied by an enemy piece other than the King. In the latter case, the enemy piece is captured. No other pieces are moved, captured, uncaptured or otherwise altered.
  • You may not play an illegal move that puts or leaves your King in check.
  • You may not play an illegal move if your opponent has already done so. So, an illegal move can't be used to escape from cheapmate.
  • Note that you cannot play an illegal move to escape from checkmate, because checkmate ends the game immediately.
If the FIDE-illegal move results in checkmate or stalemate, then the game is over. Otherwise, the opponent may declare that the move was illegal, and, according to the rules of FIDE Chess, the position is reset to just before the offending move, and the player who made the move makes another. Attempting to play an illegal move is not, in itself, grounds for a penalty or loss of game.

There is a Zillions of Games implementation of this game (should appear below in the "see also"), but it runs into "Too many moves were generated" trouble when you try to make the computer play. Also, it lets you play an illegal move at any time, but if the enemy can evade check, you lose.

Written by Robert Price
WWW page created: May 24th, 2002.