In the delightfull book of Raymond Smullyan: Chess Mysteries of Sherlock Holmes, Times Books, Random House, New York, 1994, ISBN 0-8129-2389-8, featuring chessproblems that must be solved by retrograde analysis, some monochromatic retrograde chess problems appear, i.e., problems where the positions were caused by Monochromatic chess. The personages of the book Lord and Lady Ashley always play this game in the book.
The game actually appears to be well playable, and it is nice to play this variant for a change, because it creates new and unknown problems.
In monochromatic chess, no piece may make a move in which it changes the colour of its square. As a result, rooks may move only an even number of squares, knights are immobile, kings can only move diagonally, etc. Pieces still give check on squares they cannot reach but would have been able to reach in a normal chess game. All other rules remain as in orthodox chess.
Here follows a (constructed) example game.
The game has its restrictions. After reaching the fourth (for white) or fifth (for black) row, pawns can only move forward by taking. Only castling short is possible - in theory, because the opponent should cooperate by removing the intervening knight. Knights are totally immobile.
To get rid of the last disadvantage of the game, here are three subvariants:
Play the game without the knights. Castling now is easier. An attractive way to play this game.
The knight moves as camel (Jamal) from Tamerlane chess, the large historic chess (shatranj) variant of Timur Lenk or Tamerlane. The camel moves one square diagonally and then two squares vertically or horizontally, i.e, from e4 to b3, b5, d1, d7, f1, f7, h3, or h5. Ralph Betza commented that the Jamals may be too awkward, and also perhaps too strong (1. Jb1-c4 threat 2. Jc4-f5 is a bad move; but it shows the danger of this piece), and suggested to use Daffy's for knights instead.
Another option is to give the knight the possibility to make two successive moves in one turn. However, this means that white can mate in his first move: just move the knight from b1 to b5: mate.
Instead, one can also take the modification which is described as Monochromatic Chess in the Encyclopedia of Chess Variants. In this variant, the two moves of the knight should be in the same direction, so white could start with moving his knight on b1 to d5, but this knight cannot go in this first move to any other square. This makes the knights rather weak pieces.
Ralph Betza suggested to use instead Daffy's or DA's for knights. A Daffy combines the moves of the old Arabic Dabbaba and Alfil: it can jump two squares horizontally and vertically, e.g., from d4 it can move to b2, b4, b6, d2, d6, f2, f4, and f6, even if the intervening square is occupied.
Another suggestion of Ralph Betza is to use Berolina pawns. These are pawns that move without taking one square diagonally forward, and take by moving one square straight forward. On their first move, Berolina pawns may move two squares diagonally forward and can be taken en-passant.