I honestly can't think of many. I guess Halo, as I like that series, but am not a big fan of FPS games(when they are purely FPS, not something like the new Fallouts which are heavily RPG based with the simple mechanic of FPSing). I suppose some of the older ones were good, but the stems of the FPS genre after Halo all just turned to shit in my opinion(not saying that Halo was the last good one, I'm saying Halo started what lead to the genre turning to shit). The whole, two guns, regenerating health, powerhouse thing just doesn't appeal to me, but Halo does for some reason.