The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Trine (Series) (2 members)
- Trine Games (Developer) (3 members)
- Trion Worlds (Developer) (1 member)
- Trion Worlds (Publisher) (1 member)
- Triumph Studios (Developer) (1 member)
- Trivia (Genre) (26 members)
- Tru Blu Entertainment (Publisher) (9 members)
- Turn-based (Genre) (1 member)
- Turn-based tactics (Genre) (4 members)
- Two Tribes (Developer) (1 member)
- UFC Undisputed (Series) (3 members)
- UFO Interactive Games (Publisher) (3 members)
- UIG Entertainment (Publisher) (1 member)
- UNKNOWN GAMES (Developer) (2 members)
- Ubisoft (Developer) (10 members)
- Ubisoft (Publisher) (101 members)
- Ubisoft Blue Byte (Developer) (1 member)
- Ubisoft Bucharest (Developer) (4 members)
- Ubisoft Milan (Developer) (3 members)
- Ubisoft Montpellier (Developer) (5 members)