| Title | Year | Genre |
|---|---|---|
| Obut Pétanque | 2011 | Sports |
| Obut Pétanque 2 | 2012 | Sports |
| Odin Sphere Leifthrasir | 2016 | RPG |
| Of Orcs and Men | 2012 | Action |
| One Piece - Pirate Warriors | 2012 | Beat em up |
| One Piece - Pirate Warriors 2 | 2013 | Beat em up |
| One Piece - Pirate Warriors 3 | 2015 | Beat em up |
| One Piece - Unlimited World Red | 2014 | Action |
| Operation Flashpoint - Dragon Rising | 2009 | FPS |
| Operation Flashpoint - Red River | 2011 | FPS |
| Orange Box, The | 2007 | Compilation |
| Order Up!! | 2012 | Arcade |
| Ore no Imouto ga Konnani Kawaii Wake ga Nai. Happy End | 2013 | Adventure |
| Oretachi ni Tsubasa wa Nai | 2014 | Adventure |
| Overlord - Raising Hell | 2008 | Action |
| Overlord II | 2009 | Action |
