The player directs rats to an extermination area through maze levels. The player controls Krusty the Clown who must navigate through his Krusty Brand Fun House. Each level is a puzzle in which a number of rats must be exterminated. Using different objects and obstacles, Krusty must create a path for the rats to follow, and guide them towards an extermination device. Other creatures attempt to hinder Krusty's progress; he must throw pies in order to defeat them.
In each stage the extermination devices are run by a different character: Bart, Homer, Corporal Punishment, and Sideshow Mel.