I'm not going to vote on this until I try it with a physical mouse. I'm playing it on a laptop, which doesn't do the controls justice whatsoever, however I have a couple of suggestions that might be useful. First and foremost is audio. As Ellis James Game Studio said, some music would make a massive difference, as would gunfire and injury sounds (I found some awesome royalty free music for my entry if you'd like to see what a difference it makes: https://itch.io/jam/finally-finish-something-2021/rate/873768. I also think that R is never going to be a convenient key for reloading if you're using arrow keys, so maybe left and right shift or space bar would be more logical? The shift keys are within easy reach, and the spacebar is pretty much unmissable. Lastly maybe consider controls for those that are on laptops. It's inevitably going to be harder for them to get the angles correct, but it widens your audience.