I like it, the art is nice, animations are juicy.
I like how you have to prepare for the last boss to be able to beat it. I tried my best, but i didn't beat it even after restarting it 10+ times.
Limitation is well done, each weapon consumes different amount of energy, each has its own strength and weakness, sometimes it's beneficial to shoot a weapon at nothing to kite an enemy to reduce energy consumption overall or use a sword to kill an enemy with 1hp instead of a shotgun, there are lots of strategies you can utilize to minimize energy use, well done.
Feedback:
I honestly don't have much to add, it feels very polished and the only thing that i believe your game might benefit from is a procedural difficulty where on each restart you can upgrade your character (roguelike). But you probably already know this and didn't have time to implement it.