That's really impressive. I had a go and the game logic seemed pretty spot on.
I couldn't figure out how to load C64 .PRG files in MAME so I downloaded Vice 64 for now. Anyone know if MAME/MESS supports C64 .PRG files?
Vice 64 defaults to PAL (50hz refresh) but you can toggle NTSC (60hz) in the settings and then the game speed is arcade correct as well.
The only issue I was having was overshooting ladders when walking, most likely due to control lag in the emulator itself.
Supa cool