Mad Queen chess

Mad Queen chess names a major transformation of European rules near the end of the fifteenth century. Its most visible change turned the old short-range counselor into a queen able to travel any unobstructed distance horizontally, vertically, or diagonally.

At about the same stage, the old alfil that leaped two squares gave way to the long-range bishop. With powerful queens and bishops, threats could cross the board quickly and kings faced much earlier attacks and checkmates. Checkmate means that the king is attacked and no legal defense remains.

The term does not normally denote a separate modern variant. It is a historical label for the period in which medieval chess acquired central features of today's standard game. Other rules, including castling, still took time to become uniform.