- That position is Legal!
- Damn it!

The main idea for this variant was the build an engine to create the most illegal chess games in the world.

Impossible Chess

This variant was invented in January 2000 by Joao Pedro Neto.

1. The FIDE rules apply, except in the following:
2. A moved piece (except the King) can be transformed in any piece (except the King), if and only if:
   1. The result position is an impossible FIDE position, and
   2. Some of the player's pieces must participate on it, i.e., the position would become legal if the player's pieces were arranged in other way on the board. There is one exception: if the piece changes color to create the position, however this only counts for that specific turn.
3. A player looses, if he creates a possible board position.

The 'Not So Impossible Chess' variant: Change in rule 2.1 "impossible FIDE position" by "possible FIDE position" and remove 2.2

note: When rule 2 says "any piece" this means that the piece may change its color (and the player cannot move it anymore, since it now belongs to the other player).

note: Rule 2.2 is necessary. If not, if a player creates an impossible position, the other player would take advantage of it to play without restrictions.

notation: move=x means that after 'move', the piece is transformed into piece 'x'. If the piece also changes color, append an '^' symbol.

I wish to thank Theodore Hwa (hwatheod@Stanford.EDU) for his comments and suggestions (you can check his chess retrosoftware at http://www.stanford.edu/~hwatheod/Retractor).

Sample Game

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