The Chess Variant Pages

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

The Bishop Adjustment Rule

There are some chess variants that allow their opening setups to include the bishops on the same color squares. Some players do not see the bishops on squares of the same color as a problem, or find it a good change to the orthodox chess practice. But others see this as a disadvantage, and solutions have been sought to correct the situation.

For instance, Gabriel Vicente Maura, from Puerto Rico, the creator of Modern Chess in 1968, prefered to play with both Bishops on the dark squares. Unfortunately, he realized that in order to attract new followers to his new game he needed to compromise and allow some sort of mechanism to allow a Bishop to switch to the light squares to encourage conservative Ortodox Chess players to try his variation.

The result was Maura's original Bishop Adjustment Rule, which consisted in exchanging the square of one of the Bishops with either of the adjacent major pieces - the Queen or the Queen's Knight on the right, or the Prime Minister or Minister's Knight to the left - as long as neither of the pieces being exchanged had been moved from their original squares. The players had four ways to do the adjustment, but were only allowed to do it one time throughout the game, and only if they wished to.

Another solution to the Bishops starting on the same color was proposed by Carlos Cetina from Mexico in 1983, the 'Bishops Conversion Rule'.

In 2008 while I was creating the new variant Modern Random Chess (MRC), based on Maura's Modern Chess and Fischer Random Chess, I ran into the need of enhancing Maura's way to adjust the Bishops.

The result was the New "Generalized" Bishop Adjustment Rule, one of the four Modern Principles.

Jose Manuel Carrillo-Muniz
May 2008


The New Bishop Adjustment Rule

In 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 squares 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:
  • A Bishop that starts the game in a corner square may only adjust with the one piece adjacent to it.
  • A Bishop is allowed to swap places with a Knight, the Queen, any other non-standard piece (like the Minister in Maura's Modern Chess); a Rook and also the King!
  • When adjusting with the King, the Bishop Adjustment is considered to be a "Bishop" initiated move. It is not a King move that enables a player to move out of check. Additionally the square the King would be adjusting to, must not be under enemy attack.The King is not allowed to be in check before or after a Bishop Adjustment.
Additional consequences of the Bishop Adjustment that affect the King Castling rule:
  • If the Bishop Adjusts with the King, the King will be considered to have moved, and castling will no longer be available for the rest of the game.
  • If the Bishop Adjusts with a Rook, that rook will be considered to have moved, and castling with that rook will no longer be possible. Castling with the other Rook will still be possible provided neither the second Rook nor the King have moved.


The notation used the Bishop Adjustment is Bx<=>?y where:
  • "B" stands for Bishop.
  • "x" is the letter (a, b, c...) for the column where Bishop is located before the adjustment.
  • "<=>" is the symbol for the New Bishop Adjustment Rule.
  • "?" is the initial of the piece the Bishop is adjusting with (N for Knight, Q for Queen, M for Minister, R for Rook, K for King).
  • "y" is the letter (a, b, c...) for the column where the Bishop will be adjusting to. This letter is only required for clarification when the Bishop can adjust to two like pieces (i.e. two Knights or Rooks), otherwise this letter is omited.

Sample Bishop Adjustments

Modern Chess (MRC Position #6,944 - RNBMKQBNR)
Jose Carrillo (CAN) - Luis Menendez (PUR)
CV Game Courier, March 2008

Position after 1.e4 d6 2.f4 e6 3.Bg<=>Q Nc7 4.Nc3 Bc<=>Q (diagram above right)

MRC Position #2,264 - BNBMRQKNR
Jose Carrillo (CAN) - Luis Menendez (PUR)
CV Game Courier, May 2008

Position just after 3... e6 (diagram above left); and after 4.Ba<=>N Bg<=>M (diagram above right)

Contemporary Random Chess
Carlos Cetina (MEX) - Jose Carrillo (CAN)
CV Game Courier, May 2008

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

Prime Ministers Chess (PMC1)
Pablo Denegri (PER) - Jose Carrillo (PUR)
CV Game Courier, June 2008

Position after 1.e2 e4; and after 2.Bc<=>N Bg<=>M (both White and Black Adjust their Bishops on the 2nd move)

International Contemporary Random Chess (ICRC) Position - QRKNBRBN
Gary Gifford (USA) - Jose Carrillo (CAN)
CV Game Courier, August 2008

Position after 1. g5 d6 2. Qa3 e7 3. Nh4 Nc7 4. Nd4; and after 4... Be<=>N 5. f5 Bd7 6. Bf<=>R Qj8

Modern English Random Chess (MERC) Position - BQNRRNBK
Jose Carrillo (CAN)- Jeremy Good (USA)
CV Game Courier, June 2009

Position after 1. Bh<=>K (Kings start off exposed in the corners in this position. White adjusts and solves two issues right from move one. Protects the King and switches one of his Bishops to the light squares)

Modern Ministers Courier Chess (MMCC)
Jose Carrillo (CAN)- Jeremy Good (USA)
CV Game Courier, July 2009


Position after 1.f2 f5 2.Ni3 Ni6 3.g4 fxg4 4.e4 (diagram left) and after 4... Bd<=>M Bishop Adjustment with the c-Minister.

"Modern" variants

The existing variants (with board size) that use the Bishop Adjustment Rule are:

Other games that could benefit by the Bishop Adjustment Rule


I want to acknowledge and thank Carlos Cetina for giving me the last clue I needed to finish the definition of the new general Bishop Adjustment Rule when I was creating Modern Random Chess.

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: 2008-05-10. Web page last updated: 2009-07-12