This is a multi-game hack on a standard Galaxians PCB. It allows you to select from 8 different games and return to the menu at any time to change to a different selection.
It requires a fair amount of wiring, especially for the colour prom replacement, but if you fancy giving it a go, then email me for files and instructions.
power-up should give you a menu listing the 8 available games. Select which game you wish to play using joystick, press fire to start the game.
to return to the menu to select another game, simply hold both start 1 and start 2 at the same time.