You know those annoying little crawling zombies that crawl really fast and emit gas? When you kill them they make you unable to see, which if you're in a corner, makes you pretty much die from the other zombies. They're called gas zombies, and they only appear when you turn on the power in Kino der Toten(not in any other map).That's why you keep the power off until you have enough money to get pack of punch, you want to turn on traps, or want to find out where the ? item box is. There are 3 rules to follow when trying to kill gas zombies.
1. keep far away from their smoke; if you have a thunder gun/zues cannon it is very helpful for this rule.
2. kill the gas zombies first; always go for the gas zombies before the regular zombies.(this rule does not apply in dog rounds)
3. keep moving; do not stay in a corner unless you are following a specific stratagy to do so. WARNING- do not try to impress your friends and try to run through the smoke. Quoting one of my favorite movies-"One more shot to the head and she would have avoided being a human happy meal."
I hope this helped! Please post a comment if you have another way to kill gas zombies.