Well, it's playable now. It's got robotron-style movement, with seperate controls for moving and firing. Moving actually uses an analog joystick, which can allow speed control, but I haven't actually hooked that up yet.
The only thing that's really missing is sound. It writes sample numbers to a port, so there must have been an additional audio board. Hopefully we can dig up more info on this, if the board and/or ROM images still exist anymore.