| System (Setting) | Publications | Articles |
|---|---|---|
| Machina Arcana | 9 | 9 |
| Macho Women With Guns | 4 | 4 |
| Mad Love | 1 | 1 |
| Madness at Midnight | 1 | 1 |
| Mage: The Ascension | 1 | 1 |
| Man-O-War | 1 | 1 |
| Mansions of Madness | 18 | 18 |
| Mercenaries, Spies and Private Eyes | 0 | 1 |
| MERP | 1 | 1 |
| Mikatonic University: The Restricted Collection | 1 | 1 |
| MiniMonFa | 1 | 1 |
| Minions of Cthulhu | 1 | 1 |
| Miskatonic Madness | 1 | 1 |
| Miskatonic School for Boys | 1 | 1 |
| Miskatonic School for Girls | 2 | 2 |
| Monopoly | 1 | 1 |
| Monsters Vs Heroes | 1 | 1 |
| Mountains of Madness | 1 | 1 |
| Multiversum | 1 | 1 |
| Munchkin | 43 | 43 |
| Museum | 1 | 1 |
| The Music of Erich Zann | 1 | 1 |
| Mythic Wars | 1 | 1 |
| Mythos | 90 | 1893 |
| Mythos Board Game | 2 | 2 |
| Mythos Miniatures | 1 | 1 |
| Mythos Tales | 2 | 2 |