I really like this concept! Great job on making the movement feel solid, rage enducing, but also feel fair: that's pretty hard but you pulled it off. And THANK GOD for checkpoints, because this game gets HARD after the first level, I was kind of startled by it, to be honest :P I also really liked the box mechanics, they make it just that much more interesting. Although the whole experience was hard, I still made it and was satisfied (not enraged) afterwards ;) Good job on making this!
Some feedback: the gravity starts to act weird in level 3, after the first turret, and you have to click furiously to get your egg through sometimes, then all of a sudden at some point it starts working again.