Wow, thanks for the comprehensive comment.
The "size hard to tell" complaint we've gotten quite a lot now, so if we were continue the game we would propably try to find a better hitbox (instead of just a single collider).
As for the drag-click issue, i think it's just the timer we used. If you click for more than 0.2 seconds it counts as a drag.
Slope limitation goes into a similar direction as marking the slope red when it can't be climbed, but completely preventing steep lines might feel even better. Then you wouldn't be able to draw vertical lines to make the chicken turn around, so i'm unsure about how well that would play out.
I've answered this in a nother comment as well, the order of the levels is a bit random. It's hard to judge difficulty when your'e the one making it :)
Thanks again for the feedback, it's appreciated!