you know, heres my two cents: Though you already have the map layout strict and sticking to the plan, I can't help but suggest alitte something for the final version after everythings finished.
I've come to think, how cool would it be to look out of the window of the complex/ship and see another part of the map (which would be inaccesible) and see another fight going on, something like this:
You look out the window into another window in another area of a complex and see some yellow glares of shooting from muzzleflashes around the pitch black room, along with some tracers and mabye few permenant bullet holes in the window. And every once in awhile a shadow quickly going by it. Then it would stop, then mabye 1-2 minutes later would repeat in a different pattern of firing and whatnot, then after thats done another 1-2 minutes later the first "battle" plays and so on(kindve like the snowfall in ayumi).
I think it would add a pretty cool touch to see what looks like another battle of mabye a different group of Marines exploring / eliminating the threat in other parts of the complex.
Just my input for the final version to add some cool effects
what do ya think?