| Title | Year | Genre |
|---|---|---|
| O'Leary Manager 2000 | 2000 | Soccer |
| Oddworld Adventures 2 | 2000 | Platform |
| Oha Star Dance Dance Revolution GB | 2001 | Music / Dance |
| Oha Suta Yama-chan & Raymond | 1999 | Arcade |
| Oide Rascal | 2001 | Breeding |
| Ojarumaru - Mitsunegai Jinja no Ennichi de Ojaru! | 2000 | Arcade |
| Ojarumaru - Tsukiyo ga Ike no Takaramono | 2000 | Board game |
| Original Moorhuhn Jagd, Die | 2000 | Gun shooter |
| Othello Millennium | 1999 | Puzzle |
| Other Life - Azure Dreams GB | 1999 | RPG |
| Ottifanten - Kommando Stortebeker | 2001 | Platform |
| Ou Dorobou Jing - Angel Version | 1999 | RPG |
| Ou Dorobou Jing - Devil Version | 1999 | RPG |
| Owarai Yowiko no Game Michi - Oyaji Sagashite 3 Choume | 1999 | Adventure |
