Nice!
Found it quite hard, felt like the enemies were respawning too fast and too close, the charged attack is a great idea, but I lost 90% of the HP the time I tried to use it because the enemies were swarming all the time. Also, the enemies being able to shoot from outside the visible screen felt unfair.
You've got a solid base, with a couple of adjustments this could go far.
Great aesthetics, art and music are on point, great work overall!