Krusty moves around a room, places or removes objects, and creates a route that forces rats toward traps and exits. The puzzle is active rather than purely turn-based: rats continue moving while the player works, and a misplaced block can close the only useful route. Later rooms introduce more demanding layouts and timing.

Plan the complete rat route before placing the first block, then work from the destination backward toward the entrance. Keep a clear recovery path for Krusty and avoid creating a loop that lets rats bypass the trap. Use revision-specific saves because a guide for another regional build may show different text or timing.