Absolutely dig the art style and music. My question is - why did you ruin the experience by having limited ammo that slowly recharges? You were so close :(
For the upgrade shop of course! Spend your skill points to get increased stamina, less ammo cost, faster firing speed, ext! You can also charge up stamina by using your special ability on the ground.
I can understand that logically, but the difference between set expectations and then reality of having to wait so long was a quit moment for me. So I think you should ask more people about this.