It's not just the nostalgia
When I played Duke 3d for the first time I was blown away. The graphics were amazing compared to Wolfenstein 3d and Doom, and the immersion was fantastic. I played this game for hours on end, and loved every bit of it. Duke Nukem is a total macho badass, and my teenage self was drawn to his catchy one-liners, and of course the pixelated boobies were a plus. After beating the single player I pissed off my parents to no end by tying up the phone line on the multiplayer servers. It was my first multiplayer experience, and I couldn't get enough. When I saw they were re-releasing it on Steam I had to get it. The graphics have been updated but still hold true to the original game. Really though, it's all about the gameplay. Gunning down mobs of alien bastards, blowing up crap, tipping strippers...it's still a blast 15 years later. They really pushed the limits of the build engine, and the level design was fantastic; something you don't really see in modern shooters. The multiplayer is still awesome, especially if you can get together some friends and play in a LAN. Really, if you are a fan of shooters you owe it to yourself to try out this masterpiece of gaming history.