Generating a modest subset of Chess960.

In Fischer Placement Chess Black can decide the initial positions of the kings, while White can decide the initial positions of the queens. The positions must mirror each other. Fischer Placement Chess is like standard chess except that the players can, before play begins, swap places of the king + queen and another piece. The king may not swap with any of the rooks. The queen can be swapped with one of the rooks provided that the king remains between the rooks (this is a requirement of Chess960).

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. One restriction is that the bishops mustn't end up on the same square colour, and the king cannot become a relocatee (i.e. swapped by the queen). Note that black begins by swapping his king. Alternatively he can choose to leave the position as it is (by pressing the king). The white player then mirrors black's swap. After the kings thus have been swapped the turn is still with white. White can now relocate the queen, if he so wishes, and black then mirrors this. Next white 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 or g), castling on that side is done by moving the rook instead of the king.