Roof

I start out at the bottom of the stairwell, with some pistol, and an m4. I exit the room and see this other player, who then, I instantly knew was an alien, but I didn't shoot and he shown me another weapon, an m4 with a silencer, so if need be, I could get sneaky. At the place I'm at, there's a reception desk, and two hallways, I enter the reception area and look for supplies, find nothing and the other player runs away. I exit the reception area and take the opposite hallway from him, and enter a random door. What I entered was a dusty, old, but stable hangar area that has a bunch of cargo and 5-10 humans around. I go up to them to join them, but all of a sudden there's aliens that can run quickly, and others that can run on the walls, and the team gets picked off one by one, until it's just me and two other aliens, a large disfigured one, and another one that leaves anyway. I shoot at the disfigured one with everything I have and drop my guns and go into an office space which has a broken down wall, the alien, I assume, is coming toward me to get me and I wait five seconds until a hear other people talking and run out to them, in which they pick the other aliens off and start walking to this central high-raised area.

In this area there's a place, which I think it could be a control tower, but it's locked off, and what seems to be a small machinery area which is only two stories and probably as big as a garage. I alone go inside this machinery area and go behind a door, and there one is, RIGHT next to be, but it's invisible and I smack it with a large pan that I've apparently been holding for a while a couple times and it's dead, as that happens I see a cloud of dust being quickly entered (which destroys the form so it looks like someone ran through it) and I go up to the roof, of the machinery building only to find a human being? This can't be right, it looked like someone was invisible running up, so I take my chances, and using the pan I jump as high as I can and hit the guy with all my force, he backs up, this is the alien/human that gave me that m4 with the silencer, and I continue to hit him with the pan, killing him, in which makes the humans of the game win.

Humans win and the dream ends, I wake up.