close

Monochromatic Chess

Each piece move must begin end on the same colour square it began. This is a very severe restriction to normal chess:

- Knights cannot move at all
- Pawns can only capture (after any initial double step)
- only K-side castling is legal.

On the other hand, en passant is fine and indeed often exploited in problems to help a pawn promote.

In most problems, "checks are fairy". This means that a King is only in check by enemy units standing on same-colored square, when capturing the King would be a monochromatic move. So that e.g. the two Kings can happily be in contact.

The monochromatic constraint has been used several times in the popular Sherlock Holmes book by Raymond Smullyan. However in Smullyan's compositions, checks are not fairy: the kings could not be adjacent.

Another variant relies on the concept that castling is a king's move. In this context, queenside castling is ok.