Nice work! A good gameplay loop, using your current weapon to earn enough cash to upgrade to something better.
I like that you can't spring while reloading, so the player has to be mindful about when they do so and can swap back to weaker weapons in a pinch to buy themselves some time. Pricing two weapons at $800 is a nice way to gie the player some extra choice, since that's a situation where the upgrade path can diverge. I also liked that I could go up the stairs of the towers, but this turned out to be a bad strategy for me when I got cornered there, unable to escape. :)
I wish that it was smoother to transition between weapons, mostly it's not always obvious which one you have equipped at a time since the player model is small and the only UI indicator is the ammo count. As well, (and this is probably a skill issue thing) it was rare for me to be able to handle the current group of enemies without running out of bullets and having to dash around to get enough distance to safely reload.
Some stronger sound and visual effects on hitting enemies (and getting hit by enemies) would be appreciated, both to give the player feedback and to make the combat feel more satisfying.