Controls consist of a two-position joystick and a button. The player assumes the role of Mappy, a police mouse tasked with recovering stolen items from a mansion that serves as a hideout for a gang of thieving cats. Goro (Nyamco in Japanese), large and red, is the leader, while the smaller pink Meowky cats (Mewky in Japanese) are his underlings.

The mansion contains horizontal passages closed off by doors and broken up with gaps bridged by trampolines. If a character runs off the edge of a platform, he will fall into a gap and bounce on a trampoline if one is there. Both Mappy and the cats can veer to either side and land on a platform while traveling upward, but not while falling. A trampoline will break if Mappy bounces on it four consecutive times, changing color after each bounce to indicate its status. Once Mappy lands on a platform, the trampoline reverts to its original status. He cannot be hurt by any cats while bouncing either up or down, and the cats can bounce on trampolines without breaking them.

The goal of each round is to collect all 10 stolen items, which form five pairs: stereos, televisions, Mona Lisa paintings, computers, and safes.