The concept and mechanics here are nice and innovative, a great use of what I thought was a fairly difficult theme! As others have mentioned, the dragon seems much better than the knight and the balance here could be tweaked, but this seems to be something that you have already addressed :)
The art, whilst basic, kept everything readable, clear and simple. If you intend to update it would be fun to see this without the 'developer art', but try maintain the readability of the game as is!
Awesome entry, good job :)