The player guides Mappy the police mouse through
the mansion of the cats called Mewkies (Meowky in the U.S. version)
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 of long hallways in which the stolen items are stashed.
The items are:
The items come in pairs; should Mappy get paired items one right after another,
the points value of the second matching item gets a multiplier. The more the
player retrieves matching items without dying, the bigger the multiplier gets.
Therefore, ideally a player will start with the lowest value item (100 + 100 × 2)
and proceed to the highest value items (500 + 500 × 6) in order to get the highest
value items with the biggest multiplier, for a total of 8500pts.
The second item of a pair will blink if retrieving it will yield
a multiplier. A level is completed when all the loot is retrieved.
As there are 256 rounds, like in Pac-Man and other 8-bit arcade games, the
last round's play is normal, but harder than usual. When the player finishes
the round, which is also known as "round 0," the first round appears again.