Keep moving!
I've been playing this on and off over the years, not sticking to it because I found it so brutal. I think I had it on Hard to start with, then lowered it to Medium, but still struggled. It was only a few weeks ago that I realised what I'd been doing wrong all this time. Having left it for so long, I'd forgotten exactly what I was supposed to be doing so I watched a video on YouTube to recap. I watched in amazement as this player strutted around the ship without a care in the world, and no alien in sight. Surely they were playing it on easy? Apparently not. Just to check, I watched another video and saw much the same thing. I then tried this for myself, not slowly inching around the place, but casually walking about, just doing what I needed to do. I made it to the next save point without incident on the first attempt, despite having failed dozens of times before. Honestly, I was gobsmacked. It turns out that the alien takes time to home in on you. Stay in one room too long and it'll certainly find you. Keep moving and you'll probably be fine. I haven't had time to go back to it yet, but when I do, I'll probably crank it up to Hard again.