Twomover

A twomover is a directmate with a limit of two White moves. White makes the first move, Black chooses a defense, and White must have a mating second move against every legal defense.

The correct first move is called the key. It does not have to be a check, a capture, or an obvious threat. Its job is to create a position in which every Black reply can be answered in a way that fulfills the stipulation, meaning the task set by the problem.

The notation #2 counts White moves, not individual moves by both sides. A complete line normally contains three individual moves: White, Black, then White mate. A threemover adds another White move, while a moremover begins at four.