The Skeleton Key chess set fits perfectly on our list of the most unusual and interesting chess sets. The strange chess set has been designed around the function of skeleton keys that are made of brass. The most interesting thing is that while the top of every key differentiates it from the other, the bottom of every key is the same. It means every key is designed to fit any slot on the chess board. These holes look like the the ones we have on doors that open with a key. While the whole idea of this skeleton key chess set looks innovative and unique, it will kind of trouble the players putting the keys in and taking them out, especially if it’s a blitz chess game. But still, hats off to Dave Pickett for thinking the different.