| McDonald's Treasure Land Adventure Restoration | SCD | McDonald's Treasure Land Adventure | Action > Platformer | GEN | G | Improvement | Final | 03 Jul 2017 |
| Maze Tussle | Inventor | Pac-Man | Action | NES | G | Improvement | 1.0 | 01 Jan 2001 |
| Maximum Carnage SRAM | BillyTime! Games | Spider-Man and Venom: Maximum Carnage | Action > Beat 'Em Up | GEN | O | Improvement | 1.0 | 01 Dec 2021 |
| Maxim Story Mode | caminopreacher | Castlevania: Harmony of Dissonance | Role Playing > Action RPG | GBA | G, T, GP | Complete | 1.0 | 20 Jun 2021 |
| Max the lagomorph in Streets of Rage 2 | Metal64 | Streets of Rage 2 | Action > Beat 'Em Up | GEN | G, O | Improvement | 1.1 | 16 Aug 2017 |
| Max Pimp | Googie | Bomberman | Action | NES | G, T | Improvement | 1.0 | 12 Oct 2019 |
| Maverick Revenge II | mickevincent | Mega Man 5 | Action > Platformer | NES | G, S, L | Complete | beta one | 01 Feb 2011 |
| Maui Mallard Camera Delay | MaxwelOlinda | Maui Mallard in Cold Shadow | Action > Platformer | SNES | O | Improvement | 1.0 | 07 May 2022 |
| MaternalBound Redux | ShadowOne333 | EarthBound | Role Playing | SNES | G, S, T, GP, O | Improvement | 1.1 | 22 Sep 2019 |
| MaternalBound | ShadowOne333 | EarthBound | Role Playing | SNES | G, T, O | Improvement | Omega | 15 Jan 2015 |
| Mat the Rabbit in the Magic Castle | MatTheRabbit | The Bugs Bunny Crazy Castle II | Action > Platformer | GB | G, T | Complete | 1.0 | 13 Apr 2015 |
| Mastered Esper Icon | Madsiur | Final Fantasy III | Role Playing | SNES | G | Improvement | 1.1 | 27 Mar 2022 |
| Master of Shell | EgoTrain | Super Mario World | Action > Platformer | SNES | L | Complete | 1.0 | 20 Nov 2021 |
| Master of Monsters Fix | John Osborne | Master of Monsters: Disciples of Gaia | Strategy | PSX | GP | Bug Fix | 5 | 10 Feb 2013 |
| Master Higgins Facelift | K.K. Drunkinski | Adventure Island | Action > Platformer | NES | G | Improvement | 1.1 | 24 Apr 2022 |
| Massimo | Enk | Super Mario World | Action > Platformer | SNES | G, S, L, T, GP, O | Complete | Final | 26 Jan 2012 |
| Mask in Streets of Rage 2 1.1 | Metal64 | Streets of Rage 2 | Action > Beat 'Em Up | GEN | G, T, O | Improvement | 1.1 | 09 Sep 2017 |
| Marvel Super Heroes vs Street Fighter - Hidden Character | Gledson999 | Marvel Super Heroes vs. Street Fighter | Action > Fighting | PSX | GP | Improvement | 1.0 | 16 May 2016 |
| Marvel Quiz Quest | BillyTime! Games | Super Mario World | Action > Platformer | SNES | G, S, T, GP, O | Complete | 3.0 | 20 Apr 2020 |
| Marusa no Onna Plastic surgery | Gigan | Marusa no Onna | Adventure | NES | G | Complete | 1.0 | 23 Oct 2021 |
