Loving the game and how it is presented!
I'm playing the Android version and I think I've run into a bug.
I'm at level 1 of the forest area
Completing this vertical level takes me on to this triangular level:
But completing the triangular level takes me back to the vertical level again.
Edit: Oh, my mistake. It's not the same level, just a very similar looking level. Didn't notice the difference on my little phone screen.