Doom (1993 video game)
The ability for others to create custom levels and otherwise modify the game using WAD files turned out to be a popular aspect of "Doom". Gaining the first large mod-making community, "Doom" affected the culture surrounding first-person shooters, and also the industry. Several future professional game designers started their careers making "Doom" WADs as a hobby, among them Tim Willits, who later became the lead designer at id Software.
DRL (video game)
DRL (formerly DoomRL), short for Doom, the Roguelike, is a roguelike video game developed by ChaosForge based on the first-person shooters "Doom" and "Doom II". It's been in-development since 2002 and released for Microsoft Windows, Linux and OS X. Following a cease and desist notice from "Doom" trademark owner, ZeniMax Media, the game's name was changed to "DRL" in 2016.