Duke Nukem 3D
The third chapter in the series, and the first with a 3D perspective (the original Duke Nukem and the sequel, Duke Nukem II, are side scrolling platform games). This game, set sometime in the early 21st century, begins in a ravaged LA, which was overtaken by aliens while you were abducted during Duke Nukem II. Duke, upon returning to Earth, finds himself with another mess to clean up, and another alien race that needs exterminating. Duke is a can-do hero who realizes that sometimes innocent people have to die in order to save Earth, so accuracy of gun fire is not a real concern to him. :)
This game has a long list of cool things that haven't been attempted in 3D action games, yet. The weapons, for example, kick-butt:
. There's a mine that can be placed on any wall and sends out a laser trip beam-- perfect for multiplayer games.
. There's also a shrinker ray that reduces an opponent to the size of a G.I. Joe, at which point they are foot fodder--watch them splat!
. As in Shadow Warrior, you can swim under water, and even shoot players who are standing outside the water, or vice versa.