The screaming ones are the Witches that I'm talking about. Really fucking annoying, plus they always take you down to the ground. 2nd worst are the smokers, which is the one that chokes you. Plenty of times I've been choked and the AIs couldn't do shit about it. Fat ones aren't that bad, but if you kill it the wrong way, then it attracts all of the zombies. Overall, it's still a pretty fun game, I haven't even fucked around with it on multiplayer though. But it's really only worth a rental, unless its >$30.