The artwork and the character animation are outstanding. Worthy of a full priced game.
I love the ascetic and minimalist look of the game.
Jumping works well but I found actually moving backwards and forwards to be a bit "sticky", he seems to get stuck on slopes. Also I found it really difficult to control the height of the jump when getting past low spike ceilings. But I am just awful at platform games so it may just be me.
Overall I think it's great and hope that you go on to make this into a fully fledged game.