At first I really liked the visuals. I like the colors. but after some time I noticed how the colors were kinda a strain on the eyes. But maybe that's just me. Hitting moving enemies while jumping is a little unintuitive. There were several occasions where I thought my gun definitely lined up with their sprite and they didn't get hit. I don't know how it works, but maybe it's just that you shoot one "bullet" despite what the soundeffects and the animation say. And if you don't hit with that one it doesn't matter when you line up with an enemy during the rest of the animation? Feels like something like that.
Overall this is a really fun game. It has a good mix of difficult precise jumps and just walking through it casually, depending which route you take. But it invites the player to collect all the crystals and shoot all the enemies. if you aim to do that, you're in for a challenge, which I quite like.
I definitely see the potential for when you keep working on that and implement several new features. (Especially some kind of reward system for collecting crystals.)