Basically 1st Person Shooters are all the same, but there are key elements of difference between them. For example the Half Life mod Counterstrike is very realalist, however Quake 3 is as far from realism as you can get. I for one prefer Quake 3, but that is just me. One thing most 1st Person Shooters have in common is the Rocket Launcher. In most games Rocket Launchers are the most powerful weapon. One game, Jedi Knight 2 Jedi Outcast is quite different. What makes this game unique is the art of the game, or the light saber.
Anyone can get the Rocket Launcher and frag people, or the rifle adn snipe people, but it takes real skill to use the saber and force powers together. It is almost an art form as you have 3 saber stances and hordes of different moves that you can complete.
So if you are considering a 1st person shooter that has an art to it, consider Jedi Knight 2 Jedi Outcast.
-Benjamin Franklin