- Ocean Trader
- Oddworld: New ‘n’ Tasty
- Oddworld: Soulstorm
- Offensive
- Official Formula One Racing
- Oh No! More Lemmings
- Oil Barons
- Oil Imperium
- On the Ball: World Cup Edition
- One Must Fall 2097
- OpenTTD
- Operation Flashpoint: Cold War Crisis
- Operation Flashpoint: Dragon Rising
- Operation Flashpoint: Red River
- Operation Flashpoint: Resistance
- Operation Neptune
- Operation Wolf
- Order of Battle: World War II
- Oregon Trail, The
- Ori and the Blind Forest
- Ori and the Will of the Wisps
- Original War
- Orion Conspiracy, The
- Ostriv
- Out of the Park Baseball 22
- Outer Wilds
- Outer Worlds, The
- Outlast
- Outlast 2
- Outriders
- OutRun
- Outward
- Overcooked!
- Overcooked! 2
- Overwatch
- Overlord
- Overlord II