If you're counting games that appear in compilation packs, then
Centipede would be the big winner for me. I've got it for:
Atari 2600
Atari 5200
Atari 7800
PC (Atari Arcade Hits Vol. 1)
PC (Atari Anniversary Edition)
PC (Atari: 80 Classic Games in One)
Game Boy Advance (Atari Anniversary Advance)
PlayStation (Arcade's Greatest Hits: The Atari Collection 1)
PlayStation (Atari Annversary Edition Redux)
PlayStation (Centipede)
PlayStation 2 (Atari Anthology)
PSP (Atari Classics Evolved)
I think I might have an Intellivision version lying around somewhere, too, even though I've never actually owned an Intellivision system to play it on (bought a few rare and semi-rare cartridges in a thrift store once).
As you can see above, I own
three packages for PC, and
three packages for PlayStation that contain Centipede. If that's not crazy enough, then I should also mention that Atari: 80 Classic Games in One on PC, Atari Anthology on PS2, and Atari Classics Evolved each contain the arcade version
and the Atari 2600 version.
