The graphics and general atmosphere are excellent, and having to manually drag the elevator door does add a nice extra layer of immersion, although I did struggle aiming at the elevator buttons a bit so some sort of feedback like a hand icon in the middle of the screen could make a massive difference there.
I do feel like the map is complex for a game where you (I assume) are hunting subtle differences, but the only anomaly I ever noticed was the giant balls in one of the rooms appearing. I'm pretty sure I did more than 8 floors, so I'm assuming I got some wrong, in that case some sort of feedback on whether I got it right or wrong would be nice. I think the flashlight running out of charge doesn't really serve much purpose since there's no real downside to running out besides inconvenience.
I also feel like this could have been a bit more obviously Phase-related, as it stands the only thing I saw that connects it to Phase is the intro/story.