Really enjoyed it! Nicely done!
Some thoughts when I was playing it:
1. Too slippery, making maneuvering difficult. One solution in my mind is to give a force opposite to the direction of the character's facing direction while landing, to stablize movements.
2. Since the view is tilted at 45 degrees, when I wanted to go forward(align to the map), I have to use WA, WD, AS, SD, instead of the usual way W, A, S, D. So in this kind of counter-intuitive situation, maybe try to change the cliff terrain to ocean or lava, so that the player can see one's own shadow as a hint to adjust landing position.
Really love the hidden key, good map design, and everything.