Cool game.
The idea is simple but efficient & fun. A bit too hard maybe ? I think the game would more enjoyable with a few less ennemies or maybe making them slower ?
I kinda feel that the right click would have been better than the scroll wheel to call back the stars so that you can use 2 fingers and be more efficient (most people will have the reflex to use the same finger for both left click and scroll)
All in all, it's a cool prototype. with a few adjustement it can be a really fun play to tryhard a high score.
Good job :)