My favorite FPS of all time was "Farcry" for the PC. Amazing graphics, beautiful jungle, mountains and beach landscapes with what is still the best water I have ever seen. Cool off-road vehicles including, jeeps, dune buggys, pontoon boats and the coolest... flying a hang-glider from one mountain to another where you have to actually play with the up and down drafts to get where you want to be.
I also like that it was an FPS but you also have to sneak around like a sniper and use a lot of strategy. Just run around with guns-a-blazin and you won't last long.
Only downside is that it gets a ridiculously hard near the end and the game's ending will make you want to smash the CD over your head. Required an 800 dollar plus video card when it came out a few years ago but todays low enders should be able to run it fine.
