• OutOfTheBit Ltd
• One Legged Seagull
• One Hamsa
• Outhouz, Inc.
• Outsmart
• ON3D
• Otherworld Interactive
• Outerlight Ltd.
• Odd Meter
• Old School Blender Addicted
• Old Shack Studio
• onebraverobot
• OnionMilk
• OrtiGames/OrtiSoft
• Oscar Ortigueira López
• Out Of Bounds
• Orrery Games
• Outer Planet Studios
• Outgunned Games
• Origin8 Technologies Ltd
• Oliver Peat
• Olympic
• Outrage Entertainment
• OVERKILL - A Starbreeze Studio