Chess Variants/Anti-King Chess

Introduction
Anti-King Chess is a variant that adds a piece known as the "anti-king" to the chessboard. There are two versions of the variant, named with the Roman numerals I and II.

History
Both versions of Anti-King chess were created by chess variant creator Peter Aronson in 2002, inspired by losing chess. Inspired by previous variants that simply replaced the king with an anti-king, Aronson got the idea to have both the king and anti-king on the board to add dynamic tension to the game.

Rules
Both versions of Anti-King chess play mostly like the standard game, with the addition of the anti-king to the typical set of pieces.

The anti-king (reresented by an inverted king) moves exactly like a standard king. The difference between the two is that the anti-king must be kept attacked by enemy pieces at all times, and the anti-king is considerd to be in "anti-check" if it not attacked by an opposing piece. If a player's anti-king is in anti-check and the player is unable to move the anti-king to a square where it is attacked by an enemy piece that anti-king is in "anti-checkmate" and its owner has lost the game.

Because of the unique nature of the anti-king, it cannot capture or be captured by enemy pieces. This means that the anti-king cannot deliver check to the enemy king, and likewise the enemy king cannot attack the anti-king. However the anti-king does possess the ability to capture friendly pieces.

Anti-King Chess I uses several additional rules:


 * The pawns are replaced with Berolina pawns, which move diagonally and capture forward. See the Berolina chess page for more information. Unlike in Berolina chess the Berolina pawns in this game do not get the options of a first-move double-step (and hence, there is no en passant).
 * There is no castling. Instaed, if the king or anti-king have not yet moved in the game they may amke their first move as a knight's leap to an empty square, provided it is not attacked (for the king) or attacked by the enemy (for the anti-king).

Sub-variants
This chess variant does not have any notable sub-variants.