Hi! The source code is written in ugBASIC and so the game can be compiled only for the platforms currently supported (no ZX81, BBC and PET at the moment, unless of course the game is rewritten using other development tools). I think it's possible to make a VIC-20 version, but since the text resolution is less than 32x24 (which is the resolution currently adopted for the game), the program will need to be adapted. Anyway, I'll upload downloadable versions for different platforms as soon as I successfully build and test them.