> Just a guess, any clone.
All of them?
I mean, if it's a graphics hack of Pac-Man where Pac-Man looks like Elvis and the levels are slightly different, does that count as a game HBMAME supports that's not in MAME?
If the question is "what absolutely does not have similar hardware driver in MAME" then the answer is probably more like monacogp.c and that's it.
Robbbert will be along shortly...