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This page is written by the game's inventor, Uri Bruck.

Opposition Chess

Board:

The board is made up of a 7x5 rectangle, plus two sliding 4x1 sections, one on the white player's side, and one on the black players' side. The sliding sections, sliders, can be moved left or right to any one of 4 positions. A given slider remains adjacent to the same side of the main board, and cannot be moved to a position such that any part of it is not adjacent to the main board.

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 | |k|h| |
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 |m|m|h| | | | |
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 |p|p|p| | | | |
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 | | | | |P|P|P|
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 | | | | |H|M|M|
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       | |H|K| |
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Pieces:

King - Same as FIDE King

Pawn - The pawn moves step forward, right, or left. It captures diagonally forward. The pawn promotes when reaching the other player's slider. It may only promote to a piece (Monk, or Horse) that has already been captured. If the pawn reaches the slider and no pieces or that player have been captured yet, then the pawn stays there unpromoted (it may move left or right on the slider) - once a piece is captured, the pawn immediately promotes to that piece. There is no initial double-step. At any given time, each player may have at most two Monks and two HOrses on the board simultaneously.

Horse - The Horse is a non-leaping knight. It can move either first one step orthogonally and then one step diagonally, or first one step diagonally and then one step orthogonally, provided the intervening square is vacant.

Monk - The monk can move up to 3 squares in any diagonal direction, or up to 1 square in any orthogonal direction.

The object of the game to checkmate the King.

Sliders - Instead of moving a piece the player can move his own slider on his turn. The slider can be moved from its current position to any of the other 3 legal positions (see below). The player may not move the slider while the King is checked, if moving the slider would move the King through or into check, or if an opponent piece is on the slider.

The slider as seen from the player's viewpoint and the rank nearest the player: Initially the slider is pushed all the way to the right of the player. The initial position of the slider is called position-O (or the O-position)

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There are 4 legal positions for a slider. The above O-position and also

I

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II
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III
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Written by Uri Bruck.
WWW page created: April 3, 2003.