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 opponent's pieces). With multiple royal pieces the game can be won by capturing one of them (absolute royalty), or capturing all of them (extinction royalty). The rules can also impose a limit to the number of royals that are allowed to be left in check. In Spartan chess black has two kings, and they both cannot be left in check even though they both cannot be captured in one turn. The following table shows some game pieces of unorthodox chess, from fairy chess problems and chess variants (including historical and regional ones), and the six orthodox chess pieces. The columns