Mappy was released on March 25, 1083 by Namco who also developed the game. Mappy is a side-scroll platform game.

The name “Mappy” is likely derived from mappo, a Japanese (slightly pejorative) slang term for a policeman.

Mappy features cartoon-like animals, primarily cats and mice. The game’s main character itself is a mouse. Mappy runs on Namco Super Pac-Man hardware, modified to support horizontal scrolling.

The player guides Mappy the police mouse through the mansion of the cats called the Meowkies (Mewkies in Japan) to retrieve stolen goods.

The player uses a left-right joystick to move Mappy and a single button to operate doors. The mansion has six floors, four or five in some other versions, of hallways in which the stolen items are stashed. Mappy and the cats move between floors by bouncing on trampolines at various places in the house.

A round is completed when all the loot is retrieved. If the player is too slow the game speeds up. If the player waits too long after this, the “Gosenzo” coin (a green disk shape with Goro’s face on it) will drop onto the top-middle platform and chase Mappy in a manner similar to the Meowkies, but more effectively.

The third round and every fourth round after that is a bonus round. Mappy, unbothered by the cats, must bounce across a series of trampolines, popping fifteen different suspended red balloons, with a “Goro” along the way. A bonus is awarded if all the balloons are popped before the music ends. After every bonus round, a new feature is added to the gameplay, such as bells that freeze cats.

The game supports 2 players taking turns.

The game uses a pair of Motorola 6809 CPUs with 244×88 RGB graphics.