Anti-King Chess II

Invented by Peter Aronson, 2002.

Overview

Anti-King Chess II adds an Anti-King to each side’s standard FIDE army. The Anti-King is a royal piece with inverted check: it is in check when it is not attacked by any enemy piece. A player who ends their turn with their Anti-King unattacked is checkmated and loses. Win by checkmating either the opponent’s King or the opponent’s Anti-King.

Setup

Standard 8×8 board. Each side begins with the normal FIDE complement plus an Anti-King placed in the center files.

FEN: rnbqkbnr/pppppppp/3A4/8/8/3a4/PPPPPPPP/RNBQKBNR w KQkq - 0 1

• White: King e1, Anti-King d6, Queen d1, Rooks a1/h1, Bishops c1/f1, Knights b1/g1, Pawns a2–h2
• Black: King e8, Anti-King d3, Queen d8, Rooks a8/h8, Bishops c8/f8, Knights b8/g8, Pawns a7–h7

FEN notation: A = White Anti-King, a = Black Anti-King.

Pieces

All FIDE pieces move and capture as normal. The Anti-King is a special royal piece:

Anti-King

• Moves one square in any direction (like a King).
• Is in check when it is NOT attacked by any enemy piece.
• Cannot capture enemy pieces; may only capture friendly pieces.
• Cannot be captured — it can only be mated.
• Does not give check to the friendly King.
• A hostile King adjacent to the Anti-King does not count as attacking it (Kings do not attack Anti-Kings).

Rules

All standard FIDE rules apply with these modifications:

Check and checkmate apply to both royal pieces. A player is in check if their King is attacked by an enemy piece, or if their Anti-King is not attacked by any enemy piece. A player must escape check on their turn; if they cannot, they are checkmated and lose.

Winning: Checkmate the opponent’s King (King attacked and unable to escape) or checkmate the opponent’s Anti-King (Anti-King unattacked and unable to reach an attacked square).

Pawns follow standard FIDE rules: double push from the starting rank, en passant, and promotion to Queen, Rook, Bishop, or Knight.

Castling is permitted under standard conditions.

Stalemate: a player with no legal moves but not in check is stalemated (drawn, as in standard chess).

Notes

The Anti-Kings start on d6 and d3 — directly in the path of development — so they tend to be well-covered early by natural piece deployment. This makes the opening phase more conservative than Anti-King Chess I (which uses Berolina Pawns and a scattered setup). Players must maintain coverage of their Anti-King while simultaneously pressing for mate on either of the opponent’s royal pieces.

Source: chessvariants.com/diffobjective.dir/anti-king-chess.html