This was a delightful short-but-sweet project! I love this puzzle concept, and while it didn't take me long to get through the puzzles, I thought the progression worked very smoothly and puzzles were as enjoyable as they were challenging. The only thing I would change in its current state would be to add some SFX and to give bonus objectives for levels, such as a move or time goal. I'll also add - I never actually managed to get the game full-screen. That might be user error, but in full-screen the game still only took up the top-left corner of my screen? Regardless, fantastic job!