Very neat! I saw animations from this in the screenshot section and made a note to visit it later. (Which was just now!)
I don't necessarily know what makes a good first person shooter game, so take everything I say with a grain of salt. :)
First, you managed to pack a lot in for a ten day jam, so great job on that! There's enemy variety and gun variety and a large enough level which even had some twisting corridors. I liked being able to upgrade stats as well as my arsenal by purchasing things from the terminals. I was also impressed with the enemies crawling along the walls, though they did have difficulty attacking me if I stood on a pile of crates.
The guns felt different enough to use, but in terms of strength I'm only assuming that the later ones do more damage than the starting pistol. Enemies feel pretty tanky no matter what I'm shooting them with, taking several attacks to defeat even the basic creatures. I found myself needing to run away and jump around constantly to prevent myself from being overwhelmed, but that may well have been the intended design. :) It's also not always evident that enemies are getting damaged at all, sometimes (rarely) I'd see a white flash and blood splatters were only noticeable when dangerously close.
The music is nice and fits the game well. It's a bit short and, thus, noticeably repetitive, but most of the time it does well in the background when there's action to concentrate on. Likewise the sound effects are well suited, though a bit muted compared to the music.
Other than that... one time I took damage from enemies who were behind a closed door when I walked up to open it. I liked the Venus fly trap enemies but, since they're stationary, they were easy to deal with. Even in the boss battle their presence didn't feel particularly threatening. While I was fighting the boss I got low on health and thought I could sneakily go back to a terminal for health, but there were tons of bugs swarming in from everywhere which was a nice way to prevent that sort of strategy. :)