Atmosphere was well done, and I liked figuring out what to do to exit. I played very cautiously, using the sprint seldom since I assumed there was always something watching. When the monster came through the sus vent, I assumed it was chasing me from the get go (tense music also made me think that) It was a cool chase baiting it away from the door crank, opening the door just in time, but then once I got in the elevator, I did not see the button, and the monster bad day'd me.
After reading another's feedback on this page, I never realized stealth was an option! Unfortunately, the game sends you to the very start if the monster gets you. Reading the devlog, I do understand the reason for this, and I do hope you could add a save system to this game sometime, or a checkpoint system.
I also thought it was very strange that the monster kills in one hit. Throughout the game, I was collecting pain killers, which implies that they would be useful, which they aren't since the only serious threat is 1-hit-KO. Only other threats up to that point afaik was a barbed wire that did minimal damage, and steam.
With some polish, I could imagine this horror game being a hit! From as far as I got, I dig the atmosphere, and the tense music in the chase was a nice touch. I like the writing of the messages as well, because they seemed practical, not just cheesy "YOU'RE NEXT" type message. I loved how M left a note about an employee that lost their keys, which is cool flavor text that doubles as a hint as well.