The concept is fun so far. The main wave mode is a bit boring because I feel overwhelmed with so many enemies coming at me, so I know I have to kick them to keep building more ammo, but kicking them takes so long and I end up getting hurt easily. Having a weapon count as life that you can pick up if dropped when hurt is a good idea.
The kick should just be the space bar while you're in the air. There doesn't seem to be any use for space bar while in air so removing "e" as kick should be much easier to control. I recommend a wave system that goes: Wave 1: One enemy. Wave 2: A few enemies. Wave 3: 5 enemies. Wave 4: few enemies. Wave 5: more enemies. Repeat Waves 4 and 5 with slight increase on both each time.
This creates that tug of war of kicking enemies one wave, and shooting them when there are a lot in the next wave, that the rules seem to cater to but is lacking in the demo. Also, waves should either last a bit longer or only start once the enemies of the current wave are dead so that it is more fair. Currently, they pile up a bit too quickly. And it should take maybe 2 kicks to kill a bat. It was hard to tell if that is the case currently but just putting it out there.
Either way, I'm loving the visuals, music, vibe and gameplay concept so far! Would love to see this fleshed out more!