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.

Cool. Maybe change the bullet sprite so its easier to see also maybe some screenshake when you shoot would ne nice. Music would of spiced it up a bit tooo. Also i wish it automatically reloaded when you use your bullets in that clip.

Nice work and fun concept.  Less subtle sound effects, clearer sprites for the bullet and ammo pick ups so they don't blend with the background would help improve the game a bit.  Also having added in-game information on the title screen or game screen for pressing R to reload is useful for players who play the game without reading the game page first, of which I'm guilty of sometimes lol.  I always find that putting as much in-game information for the player as you can makes your games more enjoyable.