I keep almost buying alien isolation and then don't. That video and you guys talking about it makes me wish I had bought . Oh well, winter is coming, maybe I can get it then. Its not like I will run out of games in my backlog before I die anyway.
If you buy it look for the mod that untethers the Xeno from you. Do that and its erratic wandering makes the random factor go up huge in more ways than one. At first it may seem not as scary, but the upside long term is you don't get desensitized by knowing it'll pop out at any moment predictably and, like Jick said, simply become an annoyance.
Back to the randomness. You make a noise and suddenly it's not expectedly coming out somewhere looking for you, and often you can make a fuck ton of noise and it won't, but then as you get used to that it'll come out over something trivial when you're totally not prepared.
I messed around with it at a spot with two non-aggressive NPCs, the one where in my first playthrough I tinkered with seeing how the noise makers worked, which ALWAYS brought the Xeno but now didn't, nor did my banging of the wrench on the wall to lure it like I'd do to save on noise makers.
In the end I wound up running around them as they freaked out jumping while banging on the walls and after a minute it finally ran up behind me having come out of the ceiling some ways away so I didn't hear it just as I turned to look it in the face. That was the first real scare the game had given me, not just a simple jump one like before, it was like waking up realizing a spider was in bed with me. After that I tried the jumping again, which took longer to bring it out, but was able to barely get into a locker as it killed the NPCs, but being a locker in this game, it eventually found me and killed me.
Short story: By not being able reliably lure it out you can become complacent and so set yourself up for real scares to happen as well as false alarms that would have brought it out looking for you 100% of the time. At the same time the mod pretty much prevents you from using the Xeno as a reliable weapon to kill others which really limits your ability to be aggressive, forcing you to be more cautious as well making you be more choosy as to when you decide to use noise makers (and if they'll even do what you plan).