Touch-move rule the player touches his rook at the same time as touching the king, he must castle with that rook if it is legal to do so. If the player completes a two-square king move without touching a rook, the player must move the correct rook accordingly if castling on that side is legal. Otherwise, the move must be withdrawn and another king move made. When a pawn is moved to its eighth , once the player takes his hand off the pawn, a different move of the pawn can no longer be substituted. However, the move is not complete until
Pocket Mutation Chess chess. Instead of moving, a player can take one of their own pieces from the board and put it into the pocket, provided that the pocket is empty. If the piece is placed into the pocket from the last rank, it gets promoted to a piece of higher class. Otherwise the player has an option to mutate the piece into a different piece of the same class. The choice of mutating (or not) must be made at the time the piece is removed. White cannot use the pocket on the first move. The king cannot be placed into the pocket.