| Name | Types | |
|---|---|---|
| Ogaiht | Developer | |
| Ogdon Micro Design | Developer | |
| Ogdred | Developer | |
| OgelGames | Developer | |
| Oggzie | Developer | |
| OghamRowan | Developer | |
| Ogier | Developer | |
| Ogni-XR21 | Developer | |
| Ogniok | Developer | |
| Ogre Pixel | Developer | |
| Oh | Developer | |
| OhNoItsMonroe | Developer | |
| OhRussia | Developer | |
| Ohima! Interactive | Developer | |
| OhiraKyou | Developer | |
| Ohmaigawd | Developer | |
| Ohmnivore | Developer | |
| Ohmygiggles | Developer | |
| Oil Leak Games | Developer | |
| Oingman | Developer | |
| Oink Games | DeveloperPublisher | |
| Oisin The Ginger | Developer | |
| Ojin | Developer | |
| Ok0lo | Developer | |
| Oka Doka Games | Developer | |
| Okami | Developer | |
| Okano | Developer | |
| OkeArt | Developer | |
| Okinawa_Terminal | Developer | |
| Okkoo | Developer | |
| Okomotive | Developer | |
| Oktopod | Developer | |
| OktyabrGames | Developer | |
| Okult Studio | Developer | |
| Ol Roody | Developer | |
| Olaf Lubeck | Developer | |
| Olaf Meissner | Developer | |
| OlafApha | Developer | |
| Olaowo | Developer | |
| Olbap | Developer | |
| Old Cat | Developer | |
| Old Juniper Game Studios | Developer | |
| Old Mohave Games Studio | Developer | |
| Old No-Eyes | Developer | |
| Old School Games | Developer | |
| Old Skull Games | Developer | |
| OldChap | Developer | |
| OldKnivesTale | Developer | |
| OldManYit | Developer | |
| OldPat | Developer |