Undermining (chess) Undermining (chess) Undermining (also known as removal of the guard, or removing the defender) is a chess tactic in which a defensive piece is captured, leaving one of the opponent's pieces undefended or under-defended. The opponent has the unpalatable choice of recapturing or saving the undefended piece. A possible response is to sacrifice the piece whose defense was undermined before capturing the piece which just took the defender. Kramnik–Topalov in the seventh round of the 2004 Linares chess tournament reached the diagrammed position with White to play. The black knight on a4 is defended only by the black pawn on
Pocket Mutation Chess Pocket Mutation Chess Pocket Mutation Chess is a chess variant invented by Mike Nelson in 2003. In this game a player can take a piece from the board and put it into a "pocket". The piece in the pocket can be put back on the board later. When placing the piece into the pocket the player can "mutate" the piece, i.e. change it to a different piece. The game is one of the "Recognized Chess Variants" at "The Chess Variant Pages". The starting position in this game is the same as in standard chess. Players make moves as in standard