| Conte Energy Evolution | DANGER X | Lode Runner | Puzzle | NES | G, S, L, T | Complete | 1.1 | 13 Nov 2016 |
| Conte Enegy | Flain9631 | Lode Runner | Puzzle | NES | G | Complete | 1.01 | 02 Aug 2015 |
| Constructor's Wrecking Crew | Makimura Manufacturing | Wrecking Crew | Action > Platformer | NES | O | Improvement | 1.0 | 18 Dec 2013 |
| Constructor's Lode Runner | Makimura Manufacturing | Lode Runner | Puzzle | NES | G, O | Improvement | 1.0 | 18 Dec 2009 |
| Consistently Consistent Cannon | Bobolicious81 | Metroid II: Return of Samus | Action Adventure | GB | G | Bug Fix | 1.0 | 01 Sep 2020 |
| Conker's High Rule Tail | SePH | The Legend of Zelda: A Link to the Past | Action Adventure | SNES | G, S, L, T, GP, O | Complete | 1.2.7b | 06 Dec 2017 |
| Condensed Spell List | GrayShadows | Final Fantasy III | Role Playing | SNES | O | Improvement | 1.1 | 17 Sep 2017 |
| Conan (Button Fix) | the jabu | Conan | Action Adventure | NES | GP | Improvement | 1.0 | 30 Dec 2014 |
| Complete Silence status fix | ajkmetiuk | Final Fantasy: Mystic Quest | Role Playing | SNES | GP | Bug Fix | 1.0 | 06 Feb 2022 |
| Communist Mario 3 | KP9000 | Super Mario Bros. 3 | Action > Platformer | NES | G, S, T, GP | Complete | 1.3.2 | 01 Nov 2018 |
| Communist Mario | Setz | Super Mario Bros. | Action > Platformer | NES | G, L, GP | Complete | 2.0 | 03 Apr 2015 |
| Comix Zone SRAM | BillyTime! Games | Comix Zone | Action > Beat 'Em Up | GEN | O | Improvement | 1.1 | 27 Apr 2021 |
| Comix Zone - Calcium kid edition | Vikfield | Comix Zone | Action > Beat 'Em Up | GEN | GP | Improvement | 1.0 | 13 May 2019 |
| Columns Hi-Score SRAM | BillyTime! Games | Columns | Puzzle | GEN | O | Improvement | 1.0 | 26 Sep 2021 |
| Colour Hack for Aladdin-Remix ROM (2019) without Portuguese Translation | Rod Merida | Disney's Aladdin | Action > Platformer | GEN | G | Improvement | 1.01 | 15 Dec 2020 |
| ColorPaletteHack | GrimmZoner | Rings of Power | Role Playing | GEN | G | Improvement | 1.0 | 12 May 2022 |
| Colored Samus Item Window | RealRed | Super Metroid | Action Adventure | SNES | G | Improvement | 1.0 | 19 Oct 2014 |
| Colorblind Dr. Mario | TheKMan | Dr. Mario | Puzzle | NES | G | Improvement | 1.0 | 30 Dec 2020 |
| Color Wheel | Leet Sketcher | Final Fantasy III | Role Playing | SNES | G | Improvement | 1.5 | 15 Oct 2017 |
| Color Restoration Patch | Novalia Spirit | Final Fantasy VI Advance | Role Playing | GBA | G | Improvement | 1.01 | 19 Sep 2012 |
