Starts with the letter 'O'
- OOmost Chess. All movement in this variant is a form of castling. (8x8, Cells: 64)
- Orda Chess. Asymmetric variant where one army has pieces that move like knights but capture differently.
- Overkill Chess. Paired pieces are compounds of 2 FIDE elements, King's partner of all three. (8x8, Cells: 64)
- Overprotection Chess. If an attacked piece is more often defended than it is attacked, it gains extra powers. (8x8, Cells: 64)
|4 'Game' entries listed||1 'Each player has a different army' entry listed|
Total items listed: 4