I love Mappy. He's a plucky little police mouse, chasing and being chased by a nasty gang of kitties (endearingly called "Naughty Folks" in the arcade game's attract mode). His only defenses are the ability to open and close doors and bounce on trampolines to buy himself some time; he never gets to go on the offensive, which makes him a uniquely sympathetic figure in the videogame world. And his game is great fun, kind of Keystone Kops-meets-Tom-and-Jerry; it's not as elegant as Pac-Man, but it has some of the same feel, and its rinky-tink ragtime music is excellent for the time.
I only saw Mappy once in an actual arcade in the 1980's, at a theme park during a family trip, and I didn't last long on the single quarter I put in. But since that time I have played Mappy on the Namco Museum collection for the Playstation, the Namco Museum Remix set on the Gamecube, and most recently on the Wii Virtual Console Arcade. I always get a kick out of it and spend at least enough time with it to get on the high score board.
I love Mappy in part because it's the rare 80's arcade game that never saw a home console conversion in the US, so I never really got to spend time with it until the emulation age arrived. There was a Famicom version in Japan, and some 8-bit computer versions in the wild-and-wooly 80's UK scene (maybe just the MSX, actually). But the only home game we got here was Mappyland on the NES, which is basically Jaleco's City Connection with the Mappy characters.
I am now intrigued by a title on Namco's Virtual Console Arcade list -- Hopping Mappy. Is it just Mappyland, or am I in for something fun and fresh like Mr. Do's Castle? Only time will tell, unless I break down and actually research the thing. So far I am resisting the urge.