Super cute art and concept! The music is a lot of fun as well.
I found it tedious to change the sizes of the hedgehogs. I didn't really come across many situations where they needed to be different sizes, so having to adjust each one (with a slider that changes sizes while adjusting) made me feel less inclined to experiment.
But I really liked the mechanic of attaching and detaching them, and see a lot of potential there! Overall a really cool idea. Nice work!