Starts with the letter 'Oc'
- Octa-Ashtapada. 8x8x8 variant with powerful armies and the potential for multiple royal pieces per side. By Larry L. Smith.
- Octahedral Chess. 3d-board in octahedral form. (x9, Cells: 340) Author: Hans L. Bodlaender and Michael D. Ward. Inventor: Michael D. Ward.
- 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.
- Octopus Chess. Features the crooked slider: the Octopus and the dual path Sorcerer Snake. (10x10, Cells: 100) By Charles Daniel.
- Octopus Chess. Featuring the Sorcerer Snake, the Ninja Pawn, the Wazir Knight, the Ferz Knight and the Octopus. By Charles Daniel.
- Octopus Chess . Featuring the Octopus, the Sorcerer Snake, the Ferz Knight, the Wazir Knight and the Ninja Pawns. By Charles Daniel.
Total items listed: 7