| Overworks
| http://www.sega.com
|
| Oxygen Interactive
| http://www.oxygenint.com
|
| Outrage
| http://www.outrage.com
|
| OutLook Entertainment
| http://www.outlookentertainment.com
|
| Osiris Studios
| http://www.osirisstudios.com
|
| Origin Systems
| http://www.origin.ea.com
|
| Orbit Soft
| http://www.orbit-soft.com
|
| Opus
| http://www.opus.co.jp/
|
| Opera Software
| http://www.opera.com/
|
| Opera
| http://www.opera.com
|
| Onkio Haus
| http://www.onkio.co.jp
|
| Omega Training Group, Inc.
| http://www.omegatraining.com/
|
| Oldergames.com
| http://www.oldergames.com
|
| Oddworld Inhabitants
| http://www.oddworld.com/
|
| O~3 Entertainment
| http://www.o3entertainment.com/
|
| Overmax Studios
| http://www.o-works.co.jp
|
| OPeNBooK
|
|
| Office Koukan
|
|
| Ocean
|
|
| Otaboo
|
|
| Opera House
|
|
| OeRSTED
|
|
| ODENIS Studios
|
|
| Octagon Entertainment
|
|
| O-Two
|
|
| Onion Egg
|
|
| Ocarina-System
|
|
| Omega Micott
|
|
| Other Ocean Interactive
|
|
| Ornith
|
|
| oeFun
|
|
| O3 Entertainment
|
|
| Oracion
|
|
| Odyssey Software
|
|
| Oz Club
|
|
| Ongakukan
|
|
| Orbital Media
|
|
| Omega Products
|
|
| Obsidian
|
|
| Office Create
|
|
| On Demand
|
|
| Octagon Music
|
|
| Omiya Soft
|
|
| Omega Force
|
|