This was really unique and cool. I loved the setting of the same island but in summer(?) vs winter! The graphics and level/environmental design was fantastic and you made nice use of switching between the two islands.
The only issue I had, which I see other comments also mentioned, is that you can't really hold forward and jump since colliding into a wall seems to set your velocity to zero. I had to jump first and then hold forward at the apex instead. I think all that's needed is collisions with objects to let you slide up them instead of stopping your movement completely.