This game is very polished and really fun to play! I think you did a great job at slowing introducing the main mechanic, and then really iterating on it in different ways (i.e. great level design).
I think the length of the game was just right for a gamejam; however, I think you have something great on your hands, and I would love to see the game expanded. You definitely left me wanted to play more!
All the rendering tricks you used are pretty neat. I wanted to see how some of them were programmed, but it looks like your GitHub repository is private at the moment!