The idea is nice and it was kind of fun to play "chess" without knowing what each piece does.
The sprites are alright, if only a bit rough around the edges. However, I think that the roughness also adds some character to your game, but it's just a personal preference. Maybe I would remove the most obvious signs of freehand drawing and attention-grapping pixels/sharp edges, and use some kind of engraving look/fading/hue shifting around the letters to make them look more natural (again, these are just personal preferences/ideas).
Plus, the loading times are questionable.