I love the simple art style. The animations, the dust cloud when you jump, the level transitions, and the sounds all produced a good game feel for me. Headbutting the animated buttons to toggle on/off the platforms also added a nice and engaging puzzle element.
The sudden difficulty spike on level 4 seemed a bit out of place due to the advanced climbing technique that needs to be figured out, and it took me about 20x longer to complete than the levels before and after it. Also, having both Arrow and WASD controls would be greatly appreciated.
I rarely play jam games through to the finish, but the simple charm, sound mechanics, and polish kept me going to the end. I even had to come back and play through a few more times.
