Patrol chess

Patrol chess is a fairy chess form, mainly appearing in fairy chess problems. It was invented by Federik Hendrik von Meyenfeldt, who published in 1975 the first Patrol Chess problem in the Problemist.

Rule

The rules of orthodox chess are followed, with the following modification.

In order to capture or give check, a piece (including kings) must be `observed' by another piece of the same player. (Note that it is allowed to move a piece to a position where it would give check under standard chess rules, even if it is not observed; however, it only will actually give check when observed.)

Observing means that the piece can move to the square - for pawns, the diagonal capture movement is used; i.e., it is the usual guarding of pieces as in use of common chess.

Comment

While Patrol chess is mainly used as a problem theme, it is actually also a nice and playable chess variant. As most chess strategies still are valid in Patrol Chess, it is a chess variant for chess players - good chess players probably will also be good in Patrol Chess.