- Only After
- Only One + Windows 7 Fix
- Only Up! + Windows 7 Fix
- Ooblets – v1.0.24_e_da + Windows 7 Fix
- Open Country – v1.0.0.2636
- Open Roads
- Open Wheel Manager 2
- Operation Wolf Returns: First Mission – Build 12197373
- Operation: Polygon Storm – Deluxe Edition + DLC
- Operencia: The Stolen Sun – Explorer’s Edition
- Oppcium
- Opus Magnum – Build 7993169 (01.17.2022)
- OPUS: Echo of Starsong – Full Bloom Edition, v2.5.6 + Bonus Content
- Orange Cast: Sci-Fi Space Action Game – v.20
- orbit.industries – v1.1.9537.0
- Orcs Must Die! 3: Complete Bundle – v1.2.0.0 + 3 DLCs + Multiplayer
- Order of Battle: World War II – v9.0.6 + 16 DLCs
- Orders of Magnitude – v1.0 (Release)
- Orders of the Ruler
- Organs Please: Deluxe Edition – Build 10949045 + Bonus Content
- Ori and the Blind Forest
- Ori and the Blind Forest: Definitive Edition
- Ori and the Will of the Wisps
- Oriental Valley: Deluxe Edition + 2 DLCs + Windows 7 Fix
- Orten Was The Case
- Osiris: New Dawn – v0.5.616 (Release)
- Othercide – v7.75 + DLC + Bonus Content
- OU + Bonus Soundtrack
- Our Adventurer Guild – v1.071
- Our Life: Beginnings & Always – v1.6.0 + 7 DLCs
- OURWORLD + Windows 7 Fix
- Out of the Park Baseball 23 – v23.1 Build 45
- Out of the Park Baseball 25 – v25.1 Build 46 + Windows 7 Fix
- Out There: Oceans of Time
- Outbreak 2030 – v0.6
- Outbreak: Contagious Memories
- Outbreak: Epidemic – Deluxe Edition + 2 DLCs
- Outbreak: Shades of Horror – Chromatic Split
- Outcast: A New Beginning – v1.0.3.1 + Windows 7 Fix
- Outcast: Second Contact
- Outer Wilds: Archaeologist Edition – v1.1.10 + Echoes of the Eye DLC + Bonus Soundtrack
- Outlast 2
- Outlive
- Outliver: Tribulation + Windows 7 Fix
- Outpath – v1.0.2
- Outpost: Infinity Siege – Vanguard Edition – Build 13887315 + DLC
- Outward – v2020.12.15 + 3 DLCs
- Outward: Definitive Edition + All DLCs
- OVE: The Sword of Liberation
- Over Islands – v2.0