I've never really gotten into much other than FPS games (technically, "shooters" are the top-down spaceship/airplane games. Sometimes done from the side, too, but usually only 2D, in any case). My personal favorites are Unreal Tournament 2004 (with tons of mods out there, you're bound to find something fun about it), Return to Castle Wolfenstein (Though, that's mainly an Online game, for the really fun portions), Soldier of Fortune II (I just like being able to blow people's arms and legs off, so maybe you won't like this one a damn bit). Jedi Knight II: Jedi Outcast is a pretty damn fun game, but you have to be into FPS games or Star Wars to really like it.
I got into Starcraft a bit a while back, but it doesn't have a whole lot of offline replay value.
The PC is, sad to say, mainly a big FPS vehicle. Not many companies do more than FPS and RPG games for the PC. They're out there, but not as common as one would hope.
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Do you want ants? Because that's how you get ants.