The Best 3D shooting game EVER! Built on the "Build" Engine, Duke Nukem 3D kicked some major ass in its day, and still does so in these the years where polygons rule and framerates are priority.
Duke Nukem was the true video game bad-ass of his time, kicking the hell out of any other first person shooter hero around, including the original Quake.
What made this game such a hit were the quotes and the story line, which was pretty involved (well, as much as a video game story line about a guy having to blow up 'octabrains' and 'pig cops' can be). Oh, and how could I forget the scantly-clothed women!
A few of the Best lines from Duke Nukem 3D were the always anticipated "Groovy," "Bring it on," "Who wants some?" "Hail to the king baby" and my favorite "It's time to kick ass and chew bubblegum, and I'm all out of gum." A good portion of these lines are borrowed from the movie Army of Darkness, starring Bruce Campbell.
If you really want to play it now, you can buy it for like $5.99, or download it (it's very small :P).