Co-Regal Chess

Setup

Pieces

The players start out with the normal pieces which are all unchanged aside from the King and Queen.

The King gains Knight moves and can't be checked in the beginning of the game.

The Queen gains the ability to castle with the Rooks.

Two new pieces, the Prince and Princess are only available through Pawn promotion. Normal King and Queen pieces can be used for these if you can keep track of them. The Prince moves like a King but can never lose the Knight moves while a Princess moves like a Queen in standard Chess.

Rules

Co-Regal Chess is very similar to standard chess but differs in the following ways.

Firstly the objective of the game is to capture one of your opponent's royal pieces and checkmate the remaining one. Once one of the royal pieces is captured the remaining one can only move one square in any direction and be put in check. There is a new rule called en représailles or in retaliation, this is a special move for the King or Queen that allows them to recapture the piece that captured the other royal piece using their moves they lost on the move right after the capture, if it does not put them into check.

Castling has a few changes to better suit two royal pieces: the King can castle through the Queen taking her with him and vice versa. They both move two squares towards the Rook which moves one square closer to the middle to accommodate both the King and Queen.

Pawns can no longer promote to Queens and can instead promote to Princesses/Princes.

Optional rules

There are two optional moves, to be agreed upon before the game:

Bishop conversion:  Bishops can convert enemy Pawns that are adjacent to the friendly King or Queen. This moves the Bishop diagonally towards the Pawn until they are adjacent to them, they cannot convert a pawn twice in a row.

Knight imprisonment:  Knights can imprison enemy Pawns, Knights, Bishops, or Rooks.  In order to do this at least one Rook has to have not moved from the starting position and both royal pieces need to be on the board. The Knight captures the enemy piece but instead of being removed from the board the are placed where the Rook started and the Rook moves to where the Knight started. Having a piece imprisoned weakens the other pieces of that type on the board, cutting Rook and Bishop movements down to 3 and 2 squares respectively, swapping the Knights' moves with Wazir moves, and preventing Pawns from moving without capturing. Imprisoned pieces cannot move unless the Rook holding them moves or is captured. The Rook can capture the prisoner at any time and is forced to if one of the royal pieces is captured, this doesn't take up a move. If the imprisoned piece is released or executed the penalty to the other pieces of that type is removed.

Notes

The optional moves have not been tested as much as everything else, the games I have played with them didn't see very much of their use.

The Queen is still slightly more powerful than the King, playing a game with two Kings vs two Queens is like playing odds.

If you lose a royal piece promoting a Pawn to a Prince/Princess will not give your remaining King/Queen their original moves back nor remove check.

I'm not sure if a Prince vs Princess endgame is a draw, needs more testing.

Notation for Prince is Kc and Princess is Qc.

Last revised by Ben Reiniger.