I really adored this game! I loved the simplistic art and the beautiful backgrounds. The music and sound effects were nice and crisp. The idea and mechanics were so simple yet so unique. Every time a new twist on the mechanics came in, I would gasp in amazement. Overall a real neat package of a game.
All the complaints I could have about this game is due to personal skill issues. I only got to the purple playing card area before my lack of skill caught up to me. I kept getting the "switch rails" and "shoot" buttons confused because they are Z and X but, as of typing this comment, I can now see those controls can be changed.
Truly amazing work and I may come back to see if I can be a real pro gamer!
EDIT: I just remembered this hours after leaving this comment. At one point in the game, it randomly played a snippet of the Mario Bros theme before it slowly faded out. I thought it might have been another tab but there was no sound playing out of any other ones. I just thought that was funny, whether it was from this game or not.