Really cool game, awesome job. I haven't been captivated by a horror game in quite some time like that. It was really cool exploring everything, and the setting and graphics are excellent. I played it all from start to finish in about 1h30 and spent another 30 minutes trying to figure out the boss.
Some constructive feedback is that finding the pumps and resetting them was incredibly frustrating without pointers since it's easy to get turned around from the room layouts, and I knew the concept of the boss fight with the environment but I didn't know you could move your hands left and right to dodge in the 2nd phase until like 20 tries later. Having a slightly faster walking speed or stamina that recharges would greatly aid the pacing as well.