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Prime Ministers Contemporary Random Chess

Prime Ministers Contemporary Random Chess (PM-CRC), is a variation closely related to Contemporary Random Chess, played on a standard 8x8 board with a Prime Minister (Bishop + Knight) instead of a Queen in the initial random setup. In PM-CRC when a player first moves a piece from its original square, that player has the option of dropping a Queen on the vacated square as part of the player's move, à la Seirawan.

Prime Ministers Contemporary Random Chess is a 'Modern' variant, which inherits from Contemporary Random Chess the random setup (including the option of having both Bishops start up on squares of the same color), reverse symmetry, symmetric castling to either side, and the Bishop Adjustment Rule.



All pieces (minus the Queen) are randomly placed in the player’s first rank, with the only restriction that the King must be between the two rooks. It is possible for both Bishops to be on the same color squares (dark or light squares). The opponents’ pieces are placed with reverse symmetry (White’s piece at a1 is equivalent to Black’s h8, White’s b1 to Black’s g8, White’s c1 to Black’s f8, White’s d1 to Black’s e8, and so on…)

There is a Bishop Adjustment rule that is in effect only in games when both Bishops start on the same color squares in the initial random setup. This rule allows players to move one of the Bishops to the opposite color, if they so desire.

There are 2,520 different legal starting positions in Contemporary Random Chess.


In this example once the Prime Minister first leaves it's starting square, a Queen is dropped in the vacated square. Diagram above the right after 1.e2 e4 2.Mc3(Qd1)

Reverse Symmetry

In a reverse symmetrical setup the piece at the square a1 for White, is the same as the piece at h8 for Black. The piece at b1 for White is the same as the one at g8 for Black, and so on. The Pawns are in the second row of each player’s side.

Let looks at another example, from both White and Black’s point of view:


In the CRC position on the left, from White’s point of view, the Queen is on the leftmost square next to a Rook, his 2nd Rook is on his rightmost square next to a Knight, the Bishops are on their traditional Orthodox Chess initial squares, the King has a Knight to his right, and so on. Also, from White’s point of view, his opponent’s opponents King is across the board from the Knight to his right, the Bishops are across the board to each other, the Queen is on the other corner of the same long diagonal as his own Queen, and you could continue to describe the position of the opponent’s pieces in relation of White’s own.

Now look at the same CRC position in the diagram on the right, but from Black’s point of view. Every single observation made from White’s point of view above, applies as well to the point of view from Black. That's reverse symmetry!


Orthodox Chess pieces are used, plus a Prime Minister (Bishop + Knight).


Orthodox Chess rules apply when applicable. Modified Castling rules are below, as well as the new Bishop Adjustment Rule, and the rule about the Queen's drop on the board.

Dropping the Queen

When a player first moves a piece from its original square, that player has the option of placing the Queen on the vacated square, as part of the player's move.

Thus if a player played Me1-f3, he can place the Queen on e1. The move would be recorded as 1.Mf3(Qe1).

A Queen can not be dropped on the squares vacated by pieces previously moved by the Bishop Adjustment rule, as these pieces are considered to have already left their initial squares.

After castling the Queen may be dropped on either square vacated by the King or the Rook. As a consequence of the rules of castling, the Queen may be dropped on either of two different squares after Double-move castling; on one square after King-move-only or Rook-move-only castling; or not at all, after Transposition castling.

A player has up to eight opportunities to bring the Queen into play. If a player fails to do so, the unplaced Queen remains out of play.


The Prime Ministers Contemporary Random Chess castling rules are based in the Fischer Random Chess rules.

In PM-CRC, depending on the pre-castling position on the castling King and Rook, the castling manoeuvre is performed by one of these four methods:

Castling the King and Rook will be placed as if the player had castled short in Orthodox Chess, both to either side of the board. There is no long castling (O-O-O) in PM-CRC.

Thus, after c-castling (notated as O-Ob), the King is on the b-square (b1 for White and c8 for Black) and the Rook is on the c-square (c1 for White and c8 for Black). After g-castling (notated as O-Og), the King is on the g-square (g1 for White and g8 for Black) and the Rook is on the f-square (f1 for White and g8 for Black). g-castling (O-Og) is identical to Ortodox Chess short castling (O-O).

This table shows where the King and Rook end up and the notation for each type of castling.

White castles a-sideb-castlingO-ObKb1, Rc1
White castles h-sideg-castlingO-OgKg1, Rf1
Black castles a-sideb-castlingO-ObKb8, Rc8
Black castles h-sideg-castlingO-OgKg8, Rf8

However, castling may only occur under the following conditions, which are extensions of the standard rules for castling:

These rules have the following consequences:

The Bishop Adjustment Rule

In those positions where the Bishops start up in the same color squares (either both on dark or light squares), players on their turn, are allowed to convert one (and only one) of their Bishops to the opposite color square by swapping places with any piece adjacent to them. Neither the Bishop nor the piece to be adjusted with may have moved before the Bishop swap. The Bishop adjustment will count as a single turn, and a move for both the Bishop and the piece swapped with.

The Bishop Adjustment Rule is optional, and a player is not forced to use it. A player may choose to play with his Bishops on the same color squares if he so desires, even if his opponent chooses to adjust one of his Bishops.

Note that the Bishop Adjustment rule has the following consequences in PM-CRC:

Sample Bishop Adjustment

Carlos Cetina (MEX) - José Carrillo (CAN)
CV Game Courier, May 2008

After 1.e4 e5 2.c3 Be<=>R 3.Bf<=>N c5 (diagram above right)


Prime Ministers Contemporary Random Chess (PM-CRC) was created by José Manuel Carrillo-Muñiz, from Puerto Rico in 2008.

Game Courier Preset

Prime Ministers Contemporary Random Chess preset

Game Courier Logs

Game Courier Logs for Games of Prime Ministers Contemporary Random Chess

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By Jose Carrillo.
Web page created: 2008-06-07. Web page last updated: 2008-06-21