I liked the way the game assets built up as you "developed" them during the levels. I couldn't finish the Release level, though I tried quite a few times. On that note, I think being able to restart a level when you lose (e.g. with the R key), rather than return to the main screen every time, would be a good improvement. The gameplay reminded me of Audiosurf. The graphics and gameplay are simple but they work, so good effort for your first game.