Anyways, I was wanting for a long time to make a Black Mesa Type map Valve would be somewhat proud of. I added grunt sprays like the occasional "you die" and "Die, Freeman", Tank through the wall, Destroyed computer, Choke points where the military was holding out, and other stuff that you'll have to see for yourself.
EDIT: Fixed fan room, actually looks like a fan room now. New rain. No more forcing to go through vent.