Our brave MicroPatrolman has made cameo appearances in other Namco games...
Namco enjoys splicing their gaming past with their gaming present, as seen in these shots from Ridge Racer Type 4 for PlayStation (released in 1999 in the US). The Mappy cars are part of your chosen team affiliation, each based on a classic Namco game: Pac Racing Club (Pac-Man), Dig Racing Team (Dig-Dug), Racing Team Solvalou (Xevious) and Racing Club Micro Mouse Mappy. MMM is the easiest of the four and recommended for beginning players. R4 also has cameos of modern Namco PlayStation games Klonoa and Point Blank.
The trend continues in Ridge Racer V (2000) for PlayStation 2. In this shot, Mappy is treated more like an expensive sponsor.
There's our man, in the lower right corner of this screenshot of Point Blank 3 (2001, PlayStation). The Point Blank series has long featured surprise Namco cameos, but this is the first appearance of Mappy that I'm aware of. Previous Point Blanks have showcased characters from Pac Man, Dig-Dug and Galaga.
One of their weird coin-op units, Final Furlong (1997) also has many Nam-cameos. In this horse-racing game, the competing, computer-controlled horses are all named after Namco properties. You don't see much visually, but you do get to hear the announcer crying "And Mappy is in the lead, followed by Pac Man... and Time Crisis is close behind!" When I played this for the first time, Mappy was in the lead for much of the race while I was sweating away in sixth... but I believe Time Crisis eventually won. (Image from klov.com.)
Another massive coin-op unit, Namco's World Kicks (1999)... Here's the Mappy connection according to Namco Arcade: When you're at the Team Select screen, kick the ball 8 times to select the Namco '80s All-Star Team, featuring players named Pac-Man, Dig-Dug and Mappy. (Image from klov.com.)
Donkey Konga 3 (released March 2005 in Japan) is a Namco / Nintendo co-production, a rhythm game for the GameCube played with special bongo peripherals. The song list for #3 includes Mappy, as well as Dig-Dug and Pac-Man. Not to mention all the Nintendo favorites!
In 2004, Namco's PS2 game Katamari Damacy surprised the world with unconventionally addicting gameplay. The 2005 sequel, We Love Katamari, has a text-only Mappy reference. To find it, you have to roll up all of the cousins to unlock the Hidden Mode. The gag is that nobody can remember all of the cousins' names; the King of All Cosmos states that Mappy is one of his favorite cousins, even though there is no cousin named Mappy in the game. But we all know to whom the good King is referring!
Mappy in Noby Noby Boy (2009, PS3)!
Mappy and Goro both appear in Namco Bandai's downloadable game. Mappy walks around occasionally smacking things with his nightstick, while Goro (multiple Goros!) is usually seen riding a bike. Additionally, the sound effect that plays when you zoom through the Noby Noby manual is the old Mappy Microwave Door noise!
Mappy in PlayStation Home (2009, PS3)!
Now on sale in the PlayStation Home Mall for a single quarter... the Mappy Jailtime Goro T-Shirt.