Hi there, I just recently played through the demo. I found the atmosphere of the game to be quite tense, especially in the tight corridors. Visual wise the game looks nice, it makes good use of lighting and some fog effects that really help to make the environments appear creepier than they already are.
There are however a few issues I had with it. I'll preface this by saying that I know you're developing this game alone, and that this is just a demo of what's to come, but I'm not going to let that stop me from being critical about the game.
The story, where is it? Why am I in this place and why should I care? Just some vague indication of what's going would have been better than nothing. My next issue comes from the gun we're given, I don't have an issue with giving the player a weapon early on, my issue arises when the gun does absolutely nothing to the enemy. I fired all 28 bullets at the lone enemy in the game and it appears to have done nothing at all, it's as if I was slapping it with a wet noodle. There was also a point where the enemy just stopped attacking me all together and stood there doing nothing.
At the end of the day there's a few things done right here, the game looks good, plays well and keeps you on your toes. However, there's also plenty of room for improvement. In its' current state it feels hollow. You have this creepy, atmospheric environment with not much happening in it and no story to connect what does occur together. There's also the fact that the only enemy in the game is insanely hard to kill, it made for some pretty funny situations but was honestly more frustrating than it needed to be.
I don't know what you have planned for this game, only you know that. I'm basing everything I have said on what's presented in front of me and I honestly found the game to be pretty lukewarm. I don't say these things out of spite, but in hopes that one day, you can turn a mediocre game into a great one.
I hope you don't mind but I made a short let's play video of the game for my channel.