Doom

As someone whose earliest exposure to Doom was on console, and possibly one of the bottom two or three versions of the game at that, this romhack blows me away. Modders went out of their way to actually make this version playable. Not only playable, but damn good. It adds Deathmatch / Coop, all the maps, new ost, new sprites, the works. It's basically a new game.

If you have never played Doom on the Sega 32X, let me fill you in. This was meant to be a launch title, and there was precious little time to get it up and running. New system + rushed development + small dev team = 32X Doom. All the sprites face forward, even rockets - so you're essentially shooting rockets backwards. The music sounds a bit like the day after Taco Bell. The game is missing most of the maps. And my favorite - the end credits sequence dumps you into a fake DOS prompt. (It displays C:\DOOM that you cannot interact with in any way). That is why Doom 32X Resurrection is such a crazy romhack. The amount of improvement is remarkable. I can't imagine how much better it would have reviewed and sold if this is how it released.