For level 1 at first it was challenging, then I felt like I figured out a trick to make it easier. And that worked on lvl 2, but then lvl 3 did a good job of "responding" and creating a new challenge which that trick didn't work for! That was really nice design, as it let me get used to the basic mechanics before throwing me a challenge. I think with some additional levels and further/different challenges along the way this could be really great, but you have a strong start.