Woah very cool! Hey, how are you doing the C64 web player for PRG files?
thanks :) it's this great emulator/petscii art tool thing: lvllvl.com .. you can upload a .prg/.d64 into it, click 'share' and download a html copy - the emu+your program all nicely packaged up in a .zip.. which you then upload to itch and set as 'playable in browser', and it automatically puts it at the top there and it all just works.. quite magical!