Starts with the letter 'O'
- OctHex 146. Arranging the geometry of Tetrahedral Chess into an octahedron. (Cells: 146) By Charles Gilman.
- Octogonal Chess. Carrera Chess on an octogon-shaped board. (10x10, Cells: 76) By John Smith.
- One dimensional Chess Variants. A page detailing some one dimensional chess variants. Author: Hans L. Bodlaender.
- Opposition Chess. Variant on 43 square board with sliding parts. (7x7, Cells: 43) By Uri Bruck.
- Oxybeles Chess. Introducing the exceptional Oxybeles piece, which can hurl pieces over its head, on a Gustavian board (zrf available). By M Winther.
Total items listed: 5