The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Swordfish Studios (Developer) (1 member)
- Syberia (Series) (2 members)
- Synetic (Developer) (2 members)
- SystemSoft Alpha (Developer) (13 members)
- SystemSoft Alpha (Publisher) (13 members)
- System 3 (Developer) (1 member)
- System 3 (Publisher) (6 members)
- System Prisma (Developer) (1 member)
- THQ (Publisher) (55 members)
- THQ Digital Studios UK (Developer) (1 member)
- THQ Nordic (Publisher) (8 members)
- THQ San Diego (Developer) (1 member)
- THQ Studio Australia (Developer) (2 members)
- TREVA Entertainment (Publisher) (1 member)
- TSX instructions: Disabled (Config) (5 members)
- TT Fusion (Developer) (5 members)
- TT Games (Developer) (1 member)
- Tactical (Genre) (1 member)
- Tactical role-playing (Genre) (27 members)
- Taito (Developer) (3 members)