Regroupment Chess is like standard chess except that the players can, before play begins, swap places of the king + queen and another piece except the rooks. The players in turn swap, firstly, the king, secondly, the 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. 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 forgo this possibility (by pressing the king). While the turn is still with Black, he now has the option to relocate his queen. When White has made his king + queen swap (or dispensed with this possibility) he immediately starts the game by making the first move. Note that it is possible for the king to swap with the kingside bishop, but this necessitates that the queen be swapped with one of the bishops so that the bishops end up on different colours.

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 (or shorter, or none at all) leaps than usual. 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.

Curtailed castling: as an alternative rule, the king may retain its castling right only if it is placed on any of the four central files. In other words, if the king is positioned on the g or b file, the castling right is forfeited. After all, such a safety move brings certain advantages so it should cost something. This restrictive rule would also enhance strategical predictability.