Bloody hell, i'm at 29 hours of gameplay and i made a first mistake (and death) after like 20 hours of not dying a single time. I was evading a security guard, camping around a ceiling vent when alien pretty much dropped down out of the blue. I did hear it crawling somewhere above before but the noise didn't quite followed it. Despite some box being there, i was too far away. Auch. Didn't even have the time to prime the flamethrower.