Right, reckon I'm functionally complete now, time for a function freeze!
Should still have time to tidy up some of the graphics a bit more, and then balance gameplay.
The only thing I'm still not sure about is control, at the minute the turret/firing is keyboard controlled, the astronaut is mouse controlled. Which makes it a bit awkward...I was thinking of moving firing to the mouse, but I'd have to track the cursor with the turret which would probably make things too easy...will try and find a willing victim to try it out for me...
Probably won't have time to add in music though, not to worry, that was always last on the list.