Has anyone played Deus Ex? there is a PS2 version out there but the PC version is far superior. (Especially if you count in the mods and patches.)  It's an FPS with a neat, open-ended story and fairly heavy RPG elements. (Skill points, proficiencies, items, etc...) I've had it for a good long time but my old PC just couldn't handle the mod. Now I've gotten a new PC and started playing it again, it's pretty dang fun. The base game has all kinds of options for mission completion, stealth, hacking/tech, demolitions, or just basic run and gun.  The mod (TheNamelessMod) is pretty much a completely new game running on the old engine. (unreal engine 2 I think) Very funny dialogue with all kinds of references to other things, and it pokes great fun at the internet forum scene being translated into "real life." you know, flame wars, moderators, newbs (n00bz), random chat-speak, spamming, banning and such.

I highly recommend the original game if you haven't played it. It's a little slow at first and doesn't hold up to the smoothness of most modern FPSs, but it's far from linear. TheNamelessMod I also recommend, but only after you've finished the main game. Not that there's too many spoilers or anything, but that the original is totally sweet.

Not sure where you could get the game, probably ebay or something. Should be pretty cheap by now. The mod (and many others) can be found at sites like modDB or simply googling "TheNamelessMod."