Simple, yet fun game. The first couple of green balls were easy to collect but it ramped up being hard quite fast. (Or I am a noob which might also be the case)
I think graphics and audio work well together, giving it a good retro vibe.
As others said some sort of highscore, if its timer, green balls collected or anything else might be cool to have some feedback how well you as a player did.
Good job on this and keep it up!