Looks pretty cool so far man, though I agree with CJ about it being a little too dark. I also reckon you could use some other hints of colour - maybe turn one or two of the monitors in the last shot on and have the screens give out a slight glow, or have some communication pillars or whatever with lights on them protruding into the sky in the outdoor areas. You might also consider putting in some "off-angle" stuff up there - structures that have their main faces lie off the rigid 90 degree presets you are currently sticking too. The dome like structure is a good example, but more might not hurt. Nice start anyway

I really like that third screen. Though I would make the light_environment brighter - it's multiplayer, players would rather see where they're going than bask in "atmosphere." It should only FEEL dark, not actually be that dark.

Nice, rock solid,traditional HL1 feel you got going there.

/me likes.