Doom's demons are what make the series work. Sure, sprinting around a space station with a Super Shotgun in hand is thrilling, but if you don't have interesting targets to blast into a cloud of gore, what's the point? The minions of Hell are what give Doom its spicy, pulse-quickening flavor, with designs that are both threatening and intriguing. You have to remember that, for many gamers, Doom was their first-ever exposure to first-person shooting - and its enemies are what made the experience so profoundly vivifying. As you viciously unload clip after clip into hordes of growling Hellspawn, you're getting a subtle crash course in the core dynamics of the entire FPS genre.
After seeing the recent E3 Doom footage and the graphically stunning blood-and-guts confetti that results when demons and Doomguy meet, it's humbling to think that all those enemies started out as pixelated scans of clay models. And many of those demons stand the test of time, re-emerging in the new Doom with their designs - in both form and function - surprisingly intact.