The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Luxoflux (Developer) (2 members)
- M2 (Developer) (8 members)
- MLB: The Show (Series) (10 members)
- MLB 2K (Series) (7 members)
- MLB Advanced Media (Publisher) (1 member)
- MMO (Genre) (10 members)
- MOSS (Developer) (2 members)
- MOSS (Publisher) (1 member)
- MTV Games (Publisher) (9 members)
- MX vs. ATV (Series) (4 members)
- MachineGames (Developer) (1 member)
- Macross (Series) (3 members)
- Mad Catz Interactive (Publisher) (1 member)
- Mad Dog (Series) (1 member)
- Madagascar (Series) (3 members)
- Madden NFL (Series) (12 members)
- Magenta Software (Developer) (1 member)
- Magic Pixel Games (Developer) (1 member)
- Magnolia (Developer) (1 member)
- Maid meets Cat (Developer) (1 member)