Zugzwang: A German word meaning “move-need,” literally translated as “move compulsion”. This is a situation where every move a player could make causes him/her to lose (or at least worsens their position).
If either player had the ability to pass their turn at will, only moving when it was convenient – numerous positions in chess would become “stuck”, reaching a figurative stalemate.
You can see that if black could “pass the turn” in this position, and white were forced to move again (following the last move, 1.Kc6 with 2. Kb6 for example) black would escape after 2.Kb6 with 2…Kc8! and “run” to the other side of the board – waiting to “pass” again at just the right moment. If black could continue this pattern of only moving when he/she wanted to, the game would never end.
Black’s last move pinned the f1-Bishop (meaning the Bishop is attacked but can’t move – see Lesson 10) to the King on g1. Black’s move effectively ends the game, and here’s why:
White has no choice but to move 2.Kh1, allowing the immediate 2…Rxf1#. This is a perfect example of
Zugzwang, as white’s only legal move is losing on the spot, yet if a player could “pass the turn”, white’s King remain perfectly safe, forever shielded by the pinned bishop on f1; therefore, the game would never end.
