don't currently have access to my main PC with the login details for my site etc. so
from a GFX point of view the palettes for the 32x32 sprites (UFO etc.) need fixing and the starfield needs emulating (seems to be PROM based for the star layout, how they flicker is unknown)
It also looks like there might be some kind of hardware collision because right now you can't shoot the large enemies. There's a bit in the inputs that if you turn on you can shoot them, but then if you shoot in the left side of the playfield the game gets stuck drawing an explosion sequence forever.
sound CPU (which presumably does speech with a DAC like Stratovox) is not hooked up yet. There's probably some discrete sound stuff there too which is beyond my ability.