Doom (1993)

Doom (1993) created an entire genre, modding culture, and multiplayer FPS foundation that still outperforms #8 Mega Man X in longevity with active WAD creation after 30 years. John Carmack's engine was so revolutionary that 'Doom clone' remained the genre name for years. The non-linear level design rewards exploration, while the shotgun delivers the most satisfying feedback in gaming history. With over 100,000 user-made WADs and the game running on everything from pregnancy tests to ATMs, it's faster than the average retro title in adaptation—its source code release in 1997 made it 40% lighter on development restrictions than typical 90s games.