well, you started off giving credit...
so that's a good thing! It really doesn't introduce too many new things, other than some extra balls that give you different combos. I like that you tried to incorporate these, because you're very conscious that you're just trying to make a game fun, even if it's inspired by some other game. Kudos.
I think that if you wanted some suggestions, maybe changing the shapes around would distinguish it more from zuma. Maybe you could make the balls different aliens, instead of just objects. The gameplay is fun, you're right, but I think that next time you can bring some more originality to the table because you have a good start with the space theme. There's a lot you could do with it, besides what you already have.
Good start, I think some changes could make it a ten!