Companies
- Noumena Studios
- NovaLogic
- NOVECT
- Now Production
- NPD Group
- Number None
- Numskull Games
- Nuverse
- Nvidia
- NVYVE Studios
- Nyamyam
- NYKO Technologies
- Nyu Media
- Obsidian Entertainment
- Oculus
- Oculus VR
- Odd Meter
- Oddworld Inhabitants
- Odyssey Interactive
- Office Create
- Office of Film and Literature Classification
- Offworld Industries
- Ojom GmbH
- Okomotive
- Old Moon
- Omega Force
- OneMoreLevel
- Oni Press
- OnLive
- OP Productions
- Open World
- Orange Pixel
- Oreville Studios
- ORiGO Games
- OSome Studio
- Ossian Studios
- Other Ocean Interactive
- Otherside Entertainment
- Outright Games
- Outside Xbox
- Outspark Inc
- Over The Moon
- OverBorder Studio
- Overhaul Games
- Overkill Software
- Ovosonico
- Owl Cave
- Owlcat Games
- Owlchemy Labs
- Oxide Games