Left 4 Dead 2, the "Hard Eight" mutation. I've been playing that mutation for over a week, and even with difficulty set to "easy" I have yet to make it all the way through a single campaign. Half the time I'm lucky if I make it to the first safe room. Very frustrating and I find myself yelling at the game frequently (you know it's bad when you're yelling at your automated team-mates and calling them "stupid fucking useless cunts" ) but I'll beat that bastard yet.
^^^ H3LL yeah so frustrating when you can't make a level. Happened to me in Doom 3, been stuck with this humongous beast and couldn't find a way to kick it's ass off. Until I finally found a working trick. And I wasn't calling anybody stupid fucking useless cunt but me. Hahahaha