My biggest complaint is that some colors are too similar to tell apart. Adding borders around the blocks to increase the color selection is a good idea, but it's hard to tell the difference between the borders. Adding more contrast to the borders would help a lot. I really liked the introduction, it really explained the concept and rules. The music is really fitting to the theme. A few more suggestions: make every level beatable, add an undo button for if we make the level impossible, tell us when there are no moves left, and make it so that when we fail a level, we start from the beginning of that level, with perhaps a point penalty. Overall, a good game that just needs a bit of polishing.