This was a very nice take on the theme. After playing through, I do think the pieces should maybe retain their ability to move individually because it was fairly easy to get completely stuck from lack of moves. You might even be able to take it further and have it where 1+ joined pieces can move in tandem; and you could move a 5 pawns forward, for instance. Depending on where it proceeds, I don't think it even needs to be strictly Chess related.