Just a heads up I was struggling for about a week on challenge 13 so yesterday I tried to do the strategy of letting the timer run down to sudden death. Once sudden death starts the enemy worm fires directly up at the cieling and the time freezes there forever. Just a heads up. I finally beat it yesterday fair and square!

They fixed the AI teleporting onto roof at sudden death glitch but missed the shotgun one. I haven't experienced either glitch yet but I rarely let the AI get to sudden death.