This game is imitating other balance games and does it badly. You draw from a semi-random shape pool that increases with each successive challenge and the only difference in each challenge aside from that pool is the amount of time given, leniency for losing pieces, and the height that you have to stack to. There isn't nearly enough variety. Many games have pre-existing environments to build around which add more flavor, this does not. I beat one level by spiking a tall piece down on top of a tower that was almost about to collapse and I still won.
Also, things balance way too easily. I have a feeling that pieces are completely ignored after a certain point, otherwise this game would be much harder. There really isn't much to this game. You hope for tall pieces to maximize your score and balance the pieces slightly without there being any sort of puzzle element thrown in.