| Id | Name | Systems | Actions |
|---|---|---|---|
| 3490 | Opossum Country | GBC | |
| 1646 | Orb-3D | NES | |
| 2093 | Order of Twilight | Linux | |
| 3939 | Oriental Legend | Arcade | |
| 2533 | Original Memory Game | GBA | |
| 1756 | Osman | Arcade | |
| 3524 | Osomatsu-kun: Hachamecha Gekijou | Genesis | |
| 2457 | Othello | NES | |
| 2760 | Othello | A2600 | |
| 667 | Otocky | FDS | |
| 3004 | Ottos Ottifanten: Baby Brunos Alptraum | GB | |
| 188 | Out of This World | SNES | |
| 2714 | Out of This World | Genesis | |
| 3593 | Out of This World | DOS | |
| 219 | Out to Lunch | SNES | |
| 1308 | OutRun | Genesis | |
| 1341 | Over the Hedge | DS | |
| 3527 | Overclocked | NES | |
| 2235 | Overlord | NES | |
| 934 | OverTop | Arcade | |
| 3850 | P.O.W.: Prisoners of War | NES | |
| 1721 | Pac-In-Time | GB | |
| 1622 | Pac-Land | Lynx | |
| 2412 | Pac-Land | PCE | |
| 2458 | Pac-Man | NES |