Control issues
It's obious you've put in the work, but the problem is, while it's an easy game to play, over all it's hard to control. I'm shooting and bouncing back and forth, trying to jump over things and shoot send you flying, hit detiction is off, and somethmes it hard to see what you're shooting at. Having a hard time hitting what you're shooting at is tough for a shooter game. I know you're trying to emulate low gravity but even a vet like me is having problems keeping the guy steady.
Switching shots is a nice touch to up the challenge, but added with the control problems is just gonna frustrate players, espically some younger ones that won't have the patience. Also maybe a zoom out feature so you can see where the enemies are? The planet idea is cool but, most of the time you're enemies are off screen.
Sorry bud it looks well done but it's an easy game that's hard to play.