As far as FPS goes, I enjoy Soldier front, Cross fire, combat arms. They just released America's Army 3 as well. Graphics are amazing and free to play. Have fun!
Combat arms
Every single battlefield game (heroes is free btw)
Call of duty series
Avoid war rock that game is nothing but a cheap bf2 rip off... bad controles and bad physics (i mean the physics are everywhere, most items do things that make no sence whats so ever!)
Command and Conquer is a very good war game, if your looking for a FPS (First Person Shooter) try the Call of Duty Series but if your looking for a strategy game you could try Company of Heroes or even Halo Wars, Hope I helped.