The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Old School Games (Developer) (2 members)
- Omega Force (Developer) (33 members)
- Omni Systems (Developer) (1 member)
- One Piece (Series) (4 members)
- One True Game Studios (Developer) (1 member)
- Ongakukan (Developer) (2 members)
- Ongakukan (Publisher) (2 members)
- Operation Flashpoint (Series) (2 members)
- Orange Juice (Developer) (1 member)
- Other Ocean Interactive (Developer) (3 members)
- Output scaling: FidelityFX Super Resolution (FSR) (Config) (1 member)
- Over The Top Games (Developer) (1 member)
- Overkill Software (Developer) (2 members)
- PAN Vision (Publisher) (1 member)
- PGA Tour (Series) (8 members)
- PPU LLVM Java mode handling: False (Config) (0 members)
- PPU LLVM Java mode handling: True (Config) (0 members)
- PPU LLVM accurate vector NaNs: On (Config) (1 member)
- PPU decoder: Interpreter (static) (Config) (15 members)
- PPU thread count: 1 (Config) (1 member)