Selfmate

In a selfmate, White moves first but seeks a result opposite to normal chess: forcing Black to checkmate the white king. Black does not cooperate. Black tries to avoid giving that mate, and White must compel it against every defense.

The usual notation is s#n. The number states how many White moves are available to force a final Black move that gives mate. As in a directmate, where Black also resists but the goal is to mate the black king, the central idea is compulsion: the opponent resists, yet cannot avoid the stipulated result.

This clearly separates a selfmate from a helpmate, where Black and White cooperate. Selfmates can also contain virtual phases, meaning thematic lines that are analyzed but are not the actual solution: a try is a false first move that fails to a refutation, and set play shows replies already prepared before the actual first move.