Definetly try Far Cry, one of the best shooters i played in a long long time. Just don't be as disappointed as me when they bring on the aliens / mutations / whatever ...
That really blew the game for me, it was nice and realistic but they ****ed up there.
Also if you feel like playing a 3rd person shooter I recommend you try Gun.
Bit hard when you start with it but now I'm really enjoying riding around in the far west on my horse shooting indians & bandits
