It, and its immediate predecessor Wolfenstein 3D, founded the FPS genre after all. And Doom was, in a way, a Wolfenstein clone.
Doom, Quake, Half-Life, and Halo, in chronological order, are the four games I'd give the most credit to for creating what we know as the FPS genre. A lot of other games innovated on their respective formulae, but for the most part, minus a few oddballs, were/are "______ clone with Twist X". Medal of Honor gets honorary credit not for gameplay elements, but for setting off the endless run of WW2-themed shooters.