I've nearly 100 percented it, too! I have the One Shot achievement left as well as the one where you don't directly kill any humans in a single playthrough. I'm currently doing both on a single run, on easy difficulty for once because Hard is my default whenever I play through
Isolation.
The latest achievement I obtained was the secret/hidden one where you have to be killed by the Alien 100 times. Let me tell you, having only been killed by him a total of 26 times in all my playthroughs and then having to sit through 74 death animations to get that achievement was an.. experience