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This page is written by the game's inventor, Jose Carrillo.

Modern Random Chess 64

The MRC64 variation is an 8x8 board adaptation of my 9x9 Modern Random Chess (MRC) game. Modern Random Chess 64 inherits from MRC the random setup, reverse symmetry, symmetric castling to either side, and the Bishop Adjustment Rule.


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All pieces 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 MRC64.

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 MRC 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 MRC 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 exclusively used.


Orthodox Chess rules apply when applicable. Modified Castling rules are below, as well as the new Bishop Adjustment Rule.


Modern Random Chess allows each player to castle once per game, a move by potentially both the king and rook in a single move. The MRC castling rules are based in the Fischer Random Chess rules.

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

After castling, the rook and king's final positions are exactly the same positions as they would be in Maura’s Modern Chess. 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).

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 MRC64:


Modern Random Chess 64 (MRC64) was created by José Manuel Carrillo-Muñiz, from Puerto Rico in 2008.

Game Courier Logs

Game Courier Logs for Games of Modern Random Chess 64

To see actual games that have been played on-line, follow the link above.

This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.

By Jose Carrillo.
Web page created: 2008-05-11. Web page last updated: 2008-05-11