The PC gaming market in the 90s was oversaturated by shooters. Ever since Doom burst onto the scene, nearly every third shareware out there would be for some sort of shooter. Understandably, it would be easy to get sick of blasting away at monsters in first person, be it from the eyes of Doomguy or those of the Chex warrior. So when Duke Nukem 3D rolled around, it needed something to stand out from the crowd. A unique identity that would come from not just the strength of its gameplay, but the brilliance of its game world.
Duke Nukem 3D is, for the most part, set on Earth. With the exception of one episode set in a spaceship, Duke is fighting through strip clubs, hotels, banks, and jails. This presents an interesting challenge for the level designers: make a level that is not only fun, but is instantly recognizable as the setting it wants to resemble. Notably, Doom was a complete failure in this regard, with the levels still based in some form of reality (such as the UAC bases) being complete nonsense. Did you know E1M1 was supposed to be a hangar? Like, you know, a place where you keep aircraft? Not only does the map not look like a hangar, it doesn't look like anything. What reason would the UAC scientists have to construct a long hallway with some acid and stairs that lead to nothing but some power armor? Sure, it makes for a fun and iconic level, but when you take a step back it's just kind of there, a strange hallway on Mars with no rhyme or reason to it.
Lets compare that with the E1M1 of Duke Nukem 3D. Not only is it a complex and fun map filled with secrets, weapon pickups, and smart enemy placements, it's also instantly recognizable as a movie theater. There's a lobby. There's an actual theater playing ambiguously pornographic movies on the big screen. There's a projection room overlooking said theater. There's a crappy, run-down bathroom with graffiti on the stalls. There's even an arcade with a miniature "Balls of Steel" pinball game. It's the type of level that's not only fun to shoot up aliens in, it's one that you could imagine the digitized pedestrians of Duke Nukem 3D actually visiting. It's not just some maze, it's a maze with character.
And really that just about sums up what's so great about Duke Nukem 3D. Your hero wasn't a boring grizzled space marine or freedom fighter. He was a cartoonish amalgamation of the culture of the 80s and early 90s, a porn-watching, cigar-chomping, steroid-downing alien asskicker with as many shamelessly stolen movie one liners as there are bullets in the Ripper machine gun. Duke Nukem 3D was a game with a distinct personality, that not only invited you into its world inhabited solely by aliens, strippers, and action heroes, but went to some effort in convincing you that it was an actual world as opposed to some corridors on Mars.
Sure, games had done this before—in fact, any RPG with a world that didn't make any sense would be laughed right off the shelf—but Duke Nukem 3D didn't need to go that extra mile. It didn't need to set its levels in burger joints or seedy Disneyland knockoffs to be a great shooter, but their inclusion makes the game just all the more memorable. Duke may not have had another truly great adventure since he ripped the head off the Cycloid Emperor twenty years ago, but Duke Nukem 3D is just so jam-packed with character that the short life Duke had as an FPS star is enough for me.
Hail to the king, baby.