In the world of chess problems, the word "fairy" means "unorthodox", and "fairy chess" is a blanket term for a vast range of games which are based on, but different to, chess. Few of these variants are commonly played over the board; they most often appear in problems and compositions. Some of the common ways in which fairy problems deviate from standard chess rules are:

• The addition of new pieces with powers not possessed by ordinary chess pieces (for example, the grasshopper)
• Differences in the layout or size or topology (see cylindrical chess) of the board
• Additional rules restricting the range of legal moves (for an example, see maximummer).