Technical information about the Commodore VIC-1906 - Alien cartridge:
It is possible to build your own Commodore VIC-1906 - Alien replica with the information in the link below. I did spend hours and hours making and checking the PCB and schematic, but I can't guarantee that the drawings are perfect. If you build a Commodore VIC-1906 - Alien replica with this information, it is on your own risk. But if you are successful in building a replica, let me know!
The technical files for the Commodore VIC-1906 - Alien cartridge.