Great job! You have an interesting concept, music that sounds good and fits the game, and graphics that look great and are effective to gameplay. I can't shake the feeling that there is so much more you could do with this... Try adding in powerups, or mission goals, like collecting different colored cores and getting a certain color combination or something. Put something interesting and new into the game to bring it to the next level. If you put some more effort into this in another version, guarenteed you'll see a blue bar around it instead of a green one.