| Obelix |
| Oddworld Adventures |
| Oira Jajamaru! - Sekai Daibouken |
| Olympic Summer Games |
| On the Tiles - Franky, Joe & Dirk |
| Oni |
| Oni 2 - Innin Densetsu |
| Oni 3 - Kuro no Hakaishin |
| Oni 4 - Kishin no Ketsuzoku |
| Oni 5 - Innin o Tsugumono |
| Oni 5 - Innin wo Tsugumono |
| Onigashima Pachinko Ten |
| Operation C |
| Osawagase Penguin Boy |
| Othello |
| Othello World |
| Otogi Banasi Tai |
| Otoko Jyuku |
| Otto's Ottifanten |
| Out of Gas |
| Out to Lunch |
| Oyatsu Quiz - Mogu Mogu Q |
