Companies
- ORIGAME DIGITAL
- Origin8 Technologies Ltd
- Other Ocean Interactive
- Otherside Entertainment
- Ouka Studios
- Outerloop Games
- Outright Games
- Outside Xbox
- Overhaul Games
- Overkill Software
- Owlcat Games
- Packom Interactive
- Page 44 Studios
- Paintbucket Games
- Paizo
- Panasonic
- Pandemic Studios
- Panic
- Panic Button
- Papergames
- Paradox Development Studio
- Paradox Interactive
- Paradox Tectonic
- Paramount
- Paramount Digital Entertainment