heterodox problem

Heterodox problems in chess composition are a category distinct from standard problems and studies. While standard problems require White to force checkmate in a specific number of moves, and studies involve achieving a winning or drawn position in an indeterminate number of moves, heterodox problems present unusual stipulations or employ nonstandard rules and pieces.12

These "fairy chess" problems can include tasks like a "helpmate," where Black cooperates with White to achieve checkmate, or a "selfmate," where White forces Black to deliver mate. Other variations involve "retractor" problems, where a move is taken back and replaced, or "maximummer" problems, where Black must always make the longest possible move. Heterodox problems may also feature nonstandard pieces with unique powers or use boards of different sizes.1