Companies starting with O
- Oasis Games
- Obsidian Entertainment
- Ocean Drive Studio
- Oculus
- Odd Meter
- Oddworld Inhabitants
- Offworld Industries
- Oiffy
- Okomotive
- Old Moon
- Omega Force
- OneMoreLevel
- OnLive
- Onoma
- Open Lab Games
- Open Roads Team
- OPM Jobs
- OPNeon Games
- Optillusion
- Orbi Universo Team
- Orc Chop Games
- ORIGAME DIGITAL
- Original Fire Games
- Orthogonal Games
- OSome Studio
- Ossian Studios
- Other Ocean Interactive
- Otherside Entertainment
- Out of the Park Developments
- Outerloop Games
- Outerminds
- Outersloth
- Outlier
- OutOfTheBit Ltd
- Outright Games
- Over The Moon
- Over the Top Games
- OverBorder Studio
- Overhaul Games
- Overhype Studios
- Overkill Software
- Overseer Games
- Owl Cave
- Owlcat Games
- Owlchemy Labs
- Owned by Gravity
- Oxeye Game Studio
- Oxide Games