"Then he turned his enemies into cars, funniest thing I've ever seen!" Turning your enemies into cars to beat them is indeed quite humorous, and original aswell.
Besides that, being forced to go back and retrieve a new pizza each time you get hit and lose it became frustrating after a while, and during my first run before the freeze, I couldn't find the first customer at all.
But with some kind of reward system besides an increase of the "Pizza Delivered" counter, and a few more "enemy mutations", this would surely make an addicting gameplay loop!