Interference (chess) Interference (chess) In the game of chess, interference occurs when the line between an attacked piece and its defender is interrupted by sacrificially interposing a piece. It is a chess tactic which seldom arises, and is therefore often overlooked. Opportunities for interference are rare because the defended object must be more valuable than the sacrificed piece, and the interposition must itself represent a threat. In the position at left, White to play will apparently be obliged to retreat the knight from f5, because the squares to which it could advance are all guarded. However, the interference move 1.Nd6+ interrupts the
Fairy chess piece So for example, if white moves a bishop, black can follow by moving the joker as a bishop. A royal piece is one which must not be allowed to be captured. If a royal piece is threatened with capture and cannot avoid capture the next move, then the game is lost (a generalization of checkmate). In orthodox chess, the kings are royal. In fairy chess any other piece may instead be royal, and there may be more than one, or none at all (in which case the winning condition must be some other goal, such as capturing all of the