Nice job! The only thing I might suggest is possibly using (or having an option) to use more visually identifiable notation for the pieces themselves. You don't even need to create dedicated sprites for this - unicode has depictions of them.
https://en.wikipedia.org/wiki/Chess_symbols_in_Unicode
In case it's of interest, I’ve also put together a chess-education tool, a blindfold chess trainer that lets you choose the type of blindfold (partial, pieces as pucks, fade over time, etc.).
https://shahkur.specr.net
