Archon
Jumpman
Jumpman Jr.
Space Taxi
Kickstart
Deceptor
Bruce Lee
Gryphon
Cauldron
Or, sometimes I just load up Swinth and zone out for a while...
The list is damn near endless. Love the C64.
You do need access to emulated Function keys for a lot of C64 games. Not to mention, a lot of your C64 disk images will of course be "Cracked By..." one group or another, and they might have "trained" the games, giving you cheat options up front, and requiring the input of Y or N to move forward, neither of which are standard MAME keys. If you do not have a keyboard available to you near your cab, you might want to consider setting up Shifted keys in your keyboard encoder, to give you access to AT LEAST the following additional keys:
Your normal ESC key should send RunStop, use shifted keys for F1, F3, F5, F7, 'Y' and 'N'. Those should get you pretty far.
-EVEGames