Okay, Left 4 Dead 2 has a thing called "mutations". Each week a different game mode comes out. This week its "Four Swordsmen" -- everyone has swords and only swords, and there are only Special Infected (boss zombies).
I was really looking forward to this mod, although I didn't know there was going to be only special infected. I thought I would have an awesome time cutting through swaths of undead like a samurai from Hell. But the Special Infected (and the sheer number of them) add a level of difficulty that's compounded by the idiot A.I.
Valve: If you make a mod, please test it first, because I don't like having to repeat a level three times because I was caught by a Smoker on a ledge. And what did my A.I. friends do? They stood there and watch me slowly die. Wankers. I'm not sure if they were programmed to not take the big risk and save me with only melee weapons or they were just too stupid to walk around the ledge and kill the Smoker.
I'm not sure if "wankers" was directed at the game developers or the A.I., but take from it what you will.