I love the game. Its simple but yet effective. Its clear to the player what he is supposed to do while puzzles can provide a few challenges. The artstyle is great and it is impressive what some people can create out of back, white and red.
Good job.
One little note:
I did not hear anything. I don't know if it is a bug or if you did not do sounds but this is the only thing I was really missing.
**edit
I did not have it in focus. The sound design could be improved