Nice work, I like the graphics and how each level has a unique design.
I would add a reset when you fall off the platform, otherwise you have to restart the browser window.
I think I would also swap the walk animation for the jump animation, the little spaceship is cool and it seems like I spend most of my time jumping, so I would be interested to see that more.
It also seems to end abruptly, I would have it go back to the beginning.