I agree with the other commenters asking for more feedback on death and for a timer to keep track of my score. I also think you could make the movement just a little bit juicier if you tweaked the movement curve and made the SFX a little bit snappier. I think it'd be cool if the tenseness of the music amped up as the game went on -- start with small waves of small voids, and keep amping it up until you get to something like what you have now.
But with that said, you have a strong little arcade game here. I can't wait to play it after you've had a chance to make it really shine!