Congrats on the great submission!
I struggled a bit at the beginning, but actually felt I had the tools I needed to make progress, so after a few times dying at the first zombie, I did make it to round 3!
I couldn't quite figure out how to use the machines or get any upgrades. I'm guessing there's a sort of targeting I can do to find those, but it wasn't immediately obvious (even after scanning the manual). I will say, it's quite a long manual, and I think for a game jam, it's quite a lot to read and process (especially those of us that are trying to rate and play each and every game). There's probably a way to trim down and focus the game on the mechanics that feel good and make the game tense. I would really think about each and every key and whether it is worth the cognitive load for what it adds.
I found movement and firing fairly intuitive, and while I understand what aiming with ctrl did, I didn't quite understand the left/right arrow targeting while aiming. Like Patricia, I found holding control to be a bit awkward, and I would think about folks who might have motor disabilities, and would prefer not to have to hold a key down.
All of that being said, I really like the sound design (which made it clear when the round was starting), and really enjoyed this game. Congrats again, and thanks for building and sharing for the jam!