+Coin Chess
+https://msoworld.com/product/chess-variants/
+Background: Unknown inventor
+Rules:
+Normal rules apply except for the introduction of a coin (or counter)
+Black starts by placing the coin on any unoccupied square. Play then continues with players alternating turns as in normal chess.
+On their turn, a player makes any legal move but may not move onto the square where the coin has been placed. The player may move over (but not onto), the coin square.
+The player ends their turn by leaving the coin where it stands or moving the coin to a different unoccupied square.
+The coin can never be placed on an occupied square, and therefore cannot be used to protect a piece from capture
+A player wins by checkmating the opponent. Note that the coin can be used to remove escape squares from the king.