As a fellow person who writes their own engine for these things, I sympathize with the feeling of not having enough time to make more than a tech demo. I can't wait to see what you manage to make out of it in the future! The two-level shadow is neat, in particular.
Oh, and you probably know about this bug, but it seems that whenever you move in a direction that's not forward, the forward-facing sprite briefly shows up before switching to the correct one.