| Title | Year | Genre |
|---|---|---|
| Oddworld Adventures | 1998 | Platform |
| Oira Jajamaru! Sekai Daibouken | 1990 | Action |
| Olympic Summer Games - Atlanta 1996 | 1996 | Sports |
| Oni II - Innin Densetsu | 1992 | RPG |
| Oni III - Kuro no Hakaishin | 1993 | RPG |
| Oni IV - Kishin no Ketsuzoku | 1994 | RPG |
| Oni V - Innin no Tsugumono | 1995 | RPG |
| Onigashima Pachinko-Ten | 1991 | Slot machine |
| Operation C | 1991 | Action |
| Osawagase! Penguin Boy | 1990 | Arcade |
| Othello | 1990 | Puzzle |
| Othello World | 1994 | Puzzle |
| Otogi Banashi Taisen | 1995 | RPG |
| Ottos Ottifanten - Baby Brunos Alptraum | 1998 | Puzzle |
| Out of Gas | 1992 | Arcade |
| Out to Lunch | 1993 | Arcade |
| Outburst | 1993 | Fighting |
| Oyatsu Quiz Mogumogu Q | 1997 | Quiz |
