Xbox 360 - O
- Oblivion
- Obut Pétanque 2
- Of Orcs and Men
- Oh Snap!
- Omega Five
- Omerta - City of Gangsters
- Once Upon a Monster
- One Finger Death Punch
- Onechanbara - Bikini Samurai Squad
- Oneechanbara vorteX
- Onslaught
- Open Season
- Operation Darkness
- Operation Flashpoint - Dragon Rising
- Operation Flashpoint - Red River
- Operation Flashpoint 2 - Dragon Rising
- Orange Box
- Orbyx - Mystic Orbs of Chaos
- Orc Attack - Flatulent Rebellion
- Orcs Must Die!
- Orochi Warriors
- Osmos
- Otomedius Excellent
- Otomedius G
- Ougon Musou Kyoku 10
- Outdoors Unlimited
- Outfit
- Outland
- Outpost Kaloki 10
- OutRun Online Arcade
- Outsider
- Over G - Fighters
- Over G Enemy Airforce
- Over G Fighters
- Overlord
- Overlord (2007)
- Overlord 2