1) Broken airlock, AI claims it's fine

2) Scuttling sounds

3) Keep seeing a twin of yourself out of the corner of your eye

4) All other cryo-chambers full of mushrooms instead of frozen shipmates

5) No lights save for flashing/rotating warning lights in every room

6) Butt cheeks imprint visible in condensation on your cryo-chamber lid, right above where your face was.