Ah, Colonial Marines. Good times, good times.
There was one part in the game where I got a small glimpse of what it should have been. I was playing on the hardest difficulty with three other people. Complete strangers. It was toward the beginning of the game, and we were trying to escape on a ship, or blow something up, or...something. I don't know.
Anyway, we got swarmed by the aliens and it was great. We kept backing up, slowly running out of ammo, but they just kept coming. One person went down, then another. Myself and the last survivor made a break for the door, only stopping to spray a quick burst behind. I made it to the door and the other guy died on the stairs. I turned around just in time to see about three Xenomorphs jumping at me.
That was fun. The amount of panic and desperation during that one, brief moment, was what the whole game should have been like. But alas, it was not to be.