Nightmare Shift was quite a bit of fun - if that's what you'd call it. I'm new to horror as a genre, and spent quite a bit of time petrified of what was going to happen and getting scared by both the unknown and the known. There are some aspects of the game that were done well and others I feel not so much.
The ambiance you captured did so much to make me feel uneasy. It felt like those times you were somewhere, like a school, after hours and while you're allowed to be there it feels somewhat off-putting still. At every point of the game I felt this uneasiness and what occurred only amplified it. I think quite a bit of this had to do with the lighting and I really wanted to commend this aspect of the game. For what it's worth there was a portion where I spent like 4 minutes too afraid to go down a hallway. You did really good here.
The jump scares are well done and aren't overplayed. Something I often see in indie horror is the over-reliance on jump scares to be scary. The couple of ones you had were well timed and got me because I just was not expecting them. I was focused on other aspects that when they did occur they got me good, even if my reaction wasn't noticeable.
Another part of the game I liked was that if you failed the location of the numbers changed. It meant I couldn't cheese the game, and made me continue to explore the office and be on edge. Though with continued repetition this falls off.
The other side of that though is that the checkpoint is after you correctly input the code. If you fail prior to that you have to do everything that leads up to it. Which is kind of tedious. If you get to the point where you're "playing the game" I think a checkpoint should be placed there. This will speed the game up, but I think it's worth it because I accidentally misread the 7 in one of my codes as a 1 and failed a second time.
I'm going to minorly hit on the flashlight as well. If you spin fast enough you outrun it. Realistically you won't, and I never did, but I think for realism or in another game you make where it might be more important: you probably should make it so you can't outrun it.
Overall I think this game was well worth the $2 and if you're considering picking it up then I say: do it! Depending on how much you play horror games you may be able to complete it quicker than me, but whether it's 10, 15, 20, 30 minutes - I think it's worth it. My attached video has the moments I got scared timed, so if you're interested in seeing me get scared or interested in what scared me it's there for you.