The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Maximum Family Games (Publisher) (1 member)
- Maximum Games (Publisher) (1 member)
- Maximum SPURS threads (Config) (4 members)
- Medal of Honor (Series) (4 members)
- Media.Vision (Developer) (1 member)
- Media Factory (Developer) (1 member)
- Media Molecule (Developer) (4 members)
- Mega Man (Series) (2 members)
- Memories Off (Series) (2 members)
- MercurySteam (Developer) (4 members)
- Metal Gear (Series) (6 members)
- Metal Slug (Series) (3 members)
- Metalhead Software (Developer) (1 member)
- Metalhead Software (Publisher) (1 member)
- Metroidvania (Genre) (1 member)
- MicroProse (Developer) (1 member)
- Micro Graphic Image (Developer) (1 member)
- Microphone type: Disabled (Config) (1 member)
- Microsoft Studios (Publisher) (1 member)
- Microïds (Developer) (2 members)
- Middle-Earth (Series) (1 member)
- Midnight City (Publisher) (2 members)
- Midway Austin (Developer) (1 member)
- Midway Games (Developer) (3 members)
- Midway Games (Publisher) (8 members)
- Midway Studios Los Angeles (Developer) (1 member)
- Midway Studios Newcastle (Developer) (1 member)
- Mighty Rocket Studio (Developer) (1 member)
- Milestone (Developer) (16 members)
- Milestone (Publisher) (6 members)
- Millennium Kitchen (Developer) (1 member)
- Minato Soft (Developer) (1 member)
- Minato Soft (Publisher) (1 member)
- Mine Loader Software (Developer) (1 member)
- Minecraft (Series) (1 member)
- Minority Media (Developer) (1 member)
- Minority Media (Publisher) (1 member)
- Missing GameID parameter (GameID) (6 members)
- Missing GameID parameter (Infobox) (0 members)
- Missing IRD parameter (GameID) (0 members)
- Missing game mode parameter (Infobox) (732 members)
- Missing genre parameter (Infobox) (17 members)
- Missing internal resolution parameter (Infobox) (2,026 members)
- Missing release date parameter (Infobox) (108 members)
- Missing release type parameter (Infobox) (36 members)
- Mobile Suit Gundam (Series) (13 members)
- Mojang Studios (Developer) (1 member)
- Mondo Productions (Developer) (1 member)
- MonkeyPaw Games (Publisher) (2 members)
- Monkey Bar Games (Developer) (5 members)