I've got some mixed feelings on this. First of all the game absolutely gorgeous; you really nailed the pixel art! But then there's just no music at all. The core mechanic is simply genius but I don't think its utilised as well as it could be; personally what made it special was the puzzles were the player has design their shape correctly and not the challenge of platforming with weird shapes. Basically I didn't like how in the later parts of the game, the player was rail-roaded into using certain shapes.
That being said. I still think you've got something genuinely special here and I really hope that you continue to develop it; with a bit of work this could become a successful game :)