Chess-9 (Nonary Chess) is like standard chess except that the players can, before play begins, swap places of the king/queen with one of the bishop. The method generates 9 different positions, all non-mirrored (except the standard position). The players in turn swap either the king or queen. Thus, when the king is swapped (relocated), the other piece (the relocatee) ends up on the king's square. When the queen is swapped, the relocatee ends up on the queen's square. The king can only swap with the queen bishop and the queen can only swap with the king bishop.

Black begins by swapping either his king or queen. Alternatively he can forgo this possibility (by pressing the king). When White has made his king or queen swap (or dispensed with this possibility) he immediately starts the game by making the first move.

Note that the king retains his castling rights even if it has been relocated. The castling rules are simple and derive from Chess960. King and rook end up on their usual squares. The only difference is that the king can make longer leaps than usual (or shorter, or none at all). All squares between king and rook must be empty and unthreatened.
NOTE! If the king starts the game on a castling destination square (c-file), castling on that side is done by moving the rook instead of the king.

With these relocation rules the rooks remain in their natural positions, and the bishops are always positioned so that there is still a choice to develop them on either of the kingside or queenside. The knights are ready to immediately attack in the centre. This maintains the strategical ambiguity of the initial position. Non-mirrored positions ensure that there exists a strategical tension, which makes games interesting. Black relocates first. White should command the game, and in this way he can take command of the strategical situation. Remember that the resultant castling positions are always the same as in standard chess.

Chess-9 (also Nonary Chess) is designed to overcome the problem of opening monotony. The mirrored Chess960 (FRC) positions have one major drawback, namely that they tend to be lacking in strategical variety, and many times it can be hard for White to claim the initiative, strategically or tactically. It is easier to find strategically interesting positions if we go outside FRC and investigate non-mirrored positions. If we keep the criterion that the king must be placed between the rooks, then Chess960 castling rules can be retained. For instance, if the kings are initially placed on different wings, then there is already a strategical tension (even though the king can castle on both wings). The good thing is that pieces end up on non-mirrored natural positions, bishops can be developed to either wing, the knights can immediately attack in the centre, and the king is placed between the rooks. Balanced non-mirrored positions might actually be a better idea than mirrored ones.

This method of regroupment in the initial array can be used instead of randomization (cmp. Fischer Random Chess). Thus it answers to the chessplayer's predilection for remaining in control. A famous regroupment occurred in the battle between Julius Caesar and Gnaeus Pompeius, where Caesar regrouped behind his lines. The maneuver was essential as he could counter the cavalry attack on the right flank, and this was also how he won the battle.