RumbleFish10 has registered their disagreement about the genres applied to this game
After playing this recently, on Normal Mode, I felt the need to revisit this discussion. I was hoping this game would fall under one of the horror genres, but sadly, I don't think there is enough there to fit into either. However, I will say that Action-Adventure is also misleading and should be changed.
This is a great atmospheric sci-fi horror title. In terms of gameplay I would put this under Adventure based on traversing from area to area, exploration, gathering information and solving some puzzles along the way. There is hardly any action to call out in this game. Sort of similar to Blair Witch, Layers of Fear, The Medium, etc...
The other side of it are the enemy encounters, which are entirely Stealth. While not as frequent as the Adventure sections, hence why I can't back Survival Horror, this is the other game mechanic you have to use. There is no bypassing the stealth and you can't fight the monsters by any means. The distorted screen when you're too close to the enemies hinders you quite a bit during these sections. You have to crouch around quietly and strategically avoid danger, or else you will die. That's where you sort of get the Outlast/Alien feeling in those situations.
My suggestion would be Adventure + Stealth. Remove Action-Adventure.