- Operation Chromite 1950 VR
- Operation Covid-19 v1.2
- Operation Desert Road
- Operation Flashpoint – Cold War Crisis
- Operation Flashpoint GOTY Edition (Inclu ALL DLC)
- Operation Flashpoint: Dragon Rising
- Operation Flashpoint: Red River
- Operation Hardcore
- Operation KREEP v1.2
- Operation Osama Bin Laden
- OPERATION SERPENS
- Operation Sniff
- Operation Snowman
- Operation Thunderstorm
- Operation Warcade VR
- Operation: Cheek Clapper
- Operation: Global Shield
- Operation: Tango
- Operencia: The Stolen Sun
- Operencia: The Stolen Sun v1.3.8
- Ophidian
- OPPAI Academy Big, Bouncy, Booby Babes!
- Oppai Cafe
- Oppai Muse
- Oppaidius Desert Island!
- Optica
- Optika
- Opus Magnum (Update Mar 13, 2018)
- OPUS: Echo of Starsong
- OPUS: Rocket of Whispers v3.9.0
- OPUS: The Day We Found Earth v3.1.0
- Oracle
- Oracle of Forgotten Testament
- Orange Cast: Sci-Fi Space Action Game
- Orange Moon v1.5.0.0
- Orangeblood
- Orb Labs, Inc.
- Orbals
- Orbi Universo
- Orbit HD v1.0.2
- Orbit Outlaws
- ORBIT v1.6.18
- ORBITAL
- Orbital Bullet – The 360° Rogue-lite
- Orbital Defence Command
- Orbital Gear v1.3.3
- Orbital Invaders
- Orbital Racer
- Orbiz
- Orborun v1.2
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