Hmm, this was a rough one for me. Initial impressions were very strong: I think the concept is cool and the graphics/music/sound and so on felt very polished and professional. Love the cool touches like how the glow of the comet gets closer and closer. I really wanted to love it based on how good it looks and feels to just move around and shoot stuff at a basic level, but the way the rules of the game are designed brings it down, I think.
It just feels way too passive and up to random chance as to whether you can progress: all you can do is wait for pieces to fall down and then break them, hoping you get an orb from them instead of a slime. I would've loved if I could have more of a hand in creating pieces by shooting at the comet to have them come down faster or something, but all I can do is wait. Just didn't feel challenging or tense at all, as it was very easy to dodge the rocks coming down and the occasional flies that would come around were way too easy to dispatch. And then even when you get enough orbs to power the cannon to fire back, it doesn't feel satisfying: all that happens is it fires up and the bar fills up a bit with no satisfying flash or explosion or feedback of any sort to make you feel like you're fighting back.
I definitely think this has some solid and professional construction to it, but the game itself just didn't keep me hooked or excited. This one wasn't for me, but I'm looking forward to seeing what else you come out with in future as this looked like it had a lot of promise and technical know-how!