Omega Chess with an extra piece, the Fool, that mimics the movements of the last piece that was moved.

Omega Chess is played according to the same rules as orthodox chess. The 4 corner squares are used like any of the other squares on the board. There are no changes to the castling rules, but en-passant is expanded to include the pawn's initial 3-square move.
Omega Chess Advanced includes an additonal piece, the fool, that has to be dropped in the board, it can only be dropped in the first or second rank of each player. The fool imitates the movement of the last piece that was moved, with the only difference that it can not promote as a pawn or castle as a king.

Omega Chess Advanced has some differences in the dropping rules that are not followed in this adaptation. For more information on Omega Chess go to http://www.omegachess.com/