Holy shit. Alright, it's 2.40 am here right now, and I must say, by god, is this unnerving. From the hums and creaks of the environment to the slight footsteps in the background. Now, I'm gonna be real with you, I have not played the full thing yet, nor are horror games my cup of tea (I'm a scaredy cat). I'm going to wait for my wife so that I can play this with her, so we can be scared together.
The controls feel nice and smooth, the oxygen mechanic makes you always think about where you are in the area, and I love the small developer detail that (from what I can tell so far) every keycard room has a keycard so that you don't accidentally softlock yourself. OH AND DON'T FORGET THAT JUICY LIGHTING!
Overall, great job! If you don't mind, I'm still really new to game development and would love to discuss how horror games are made with you guys!