Fun game! There is very clearly a personality to the game that is unlike other shooters. Things like needing to manually chamber a round combined with the slow reload and the relaxing music made this to be a puzzle game with shooting elements instead of a shooter with puzzle elements. I don't know many other games like it, if at all. I guess the closest I can think of is the Talos Principle, and there's quite a lot of different design choices between the two.
Played through some levels, and while I was easily able to reach par, the dev time was out of my reach. I like how even the constricted indoor levels allow for multiple strategies or ways to approach a level. I didn't encounter any bugs either, although accessing the options while ingame would overlap over the ingame menu, which is a bit messy.
The fact that you can immediately repeat/restart a level without needing go to through menus or anything was a big plus.
Weapon balance might require some work (unless I'm missing some strategies), since the SMGs didn't feel particularly useful. Perhaps the Uzi (or whatever it is, I don't know guns) could have a quicker reload, or something like that.
Some time ago I saw some Anon do a redesign of your menu in a thread, which I thought was more appropriate than the standard "text on box" method. Consider changing that up a bit, especially since it's really only the button layout/visuals. The camera panning to an object (the board for credits, door on exit) was very nice.