'The rules of Anti-King Chess I are identical to those of FIDE Chess, except for the addition of an Anti-King for each side, the movement of the Pawns, the King's special move, and the initial setup.'
'The Anti-King is a King that is in check whenever it is not attacked by opposing pieces. If a player ends their turn with their Anti-King not attacked, they are checkmated and lose.'
It would be simpler to state that it is illegal to make a move leaving or placing your Anti-King in 'check', that is, not attacked by opposing pieces.
'The rules of Anti-King Chess I are identical to those of FIDE Chess, except for the addition of an Anti-King for each side, the movement of the Pawns, the King's special move, and the initial setup.'
'The Anti-King is a King that is in check whenever it is not attacked by opposing pieces. If a player ends their turn with their Anti-King not attacked, they are checkmated and lose.'
It would be simpler to state that it is illegal to make a move leaving or placing your Anti-King in 'check', that is, not attacked by opposing pieces.