It feels very aliens due to the fact we have no idea whats really going on, when things hit the fan its almost always very bad and people die, relying on the player with the motion censor, depending on turrets when things fall a part, "sealing" doors to slow the enemies down. Its little things mostly.
There isn't a whole lot of narrative lore. You're a prisoner and The Warden is making you recover certain things from this facility. The player characters should have been "retired" before the events of the game and at the end of each round you get your mental state and, as we learned in a game last night, likely hood of infection.
Most of what I've learned about the hostiles comes from the environment. The creatures are definitely nothing like the xenomorph so that's not what I meant. Whatever they are they were definitely human at one time, but they feel very much like they could be from "The Thing". It
oh, and shit like this stresses me out.