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This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2008-04-06
 Author: Hans L. Bodlaender. Inventor: Gabriel  Maura. Modern Chess. Variant on a 9 by 9 board with piece that combines bishop and knight moves. (9x9, Cells: 81) [All Comments] [Add Comment or Rating]
Greg Strong wrote on 2019-05-23 UTC

According to Pritchard's Encyclopedia, it was dissolved in 1984.  I tried some Google searches, English and Spanish, and didn't come up with anything.  Apparently, like many variants, it did died out once the inventor was no longer promoting it.

Aurelian Florea wrote on 2019-05-23 UTC

Does anyone now if there still is a world federation of modern chess?

Fergus Duniho wrote on 2018-06-30 UTC
It works when I use it. What exactly are you doing when it doesn't work right, and what exactly does it do when it doesn't work right? I need detailed bug reports if I'm to figure out what is happening and how to fix it.

Jeremy Good wrote on 2018-06-30 UTC


i believe the personal invitation feature for game courier simply hasn't been working for some time now.

Only public invites are working. 

Nonetheless: Thanks for all your great work on the website, Fergus. 

John Lawson wrote on 2018-06-28 UTC


I have a Modern Chess set, so I checked the official rules. They state that the game be played as it is set up. That is, one player has two bishops on white, the other had two bishops on black. The author seems to think this is better. The inventor permits, with prior agreement of both players before the start of the game, the "Adjustment of the Bishop".  Each player may swap one bishop with either neighboring piece, providing neither has moved.  This expressly forbidden in the official rules.

Kevin Pacey wrote on 2018-06-23 UTC

This may be a question with an obvious answer, but I was wondering if either side can commit to playing the whole game with two bishops on the same coloured squares (not including any promotions to a bishop). As there is nothing I can see that's against this possibility in the rules, I'm assuming it's allowed.

Kevin Pacey wrote on 2018-03-01 UTCGood ★★★★

Interesting use of the BN piece type combo in a variant.

Simon Jepps wrote on 2010-02-11 UTC
Thanks, Jose. ;)

Actually another option would be to place the Minister where the King side Bishop usually stands - since it is also a Bishop you wouldn't be changing anything - then you would have the opposite coloured Bishops.

You then put the King side Bishop where the Queen is and put the Queen on the other side of the King as in normal Chess.

So like this:

But yeh, 9x9's are irritating. lol.

George Duke wrote on 2009-12-03 UTC
When they refer to ''Modern,'' and ''make it Modern,'' casual-like make it a martini -- as if everybody understands it to mean Joyce's recent medley -- the real Modern Chess to a whole region of the world in the 1970s is Gabriel Maura's here. By itself Modern was having had more tournaments than CVPage has conducted for all its 3000 CVs. Tournaments in Caribbean, Mexico, Venezuela til Maura died in 1980s.

Antoine Fourrière wrote on 2009-08-14 UTC
Sorry, it seems to be working now.

Jose Carrillo wrote on 2009-07-28 UTC
Here is a Modern Chess preset that doesn't enforce the rules:


The Preset you previously created has a bug in the Bishop adjustment. If a Bishop moves first (not adjusted), the 2nd Bishop is not allowed to adjust (which it should!)

Can you check it? 



John Smith wrote on 2009-01-10 UTC
Symmetrical centre Pawn play gives White the centre. If there was mirror symmetry White could get all the possibly better central rank squares he wanted, but he does not because of rotational symmetry, which gives duplicates of each one, except the centre. Why didn't he make the Bishops able to move one square orthogonally without capturing once in the game? What's this Bishop Castling crap? Also see Mats Winther's comments. The board colours are imbalanced as aren't used in the same way. This is especially true in the original game.

Jose Carrillo wrote on 2009-01-10 UTC

>>White has the advantage of a more quickly promoting centre Pawn but it is balanced somewhat by the reverse symmetry.

White has no advantage other than the first move, just like in Orthodox Chess. Not sure where you get that the reverse symmetry somewhat balances the 'more quickly promoting centre pawn' theory of yours.

>> The imbalance between the colours, both in terms of the board and the armies, makes the game ugly,

What imbalance of armies are you talking about?

>> as does the Bishop Adjustment Rule.

Won't argue this one. There had to be a way (perhaps ugly) to solve the problem of the initial Bishops on the same color squares.

Jose Carrillo wrote on 2009-01-10 UTC
Hi Simon!

I'll try to answer your questions:

>> 1. Are there any websites dedicated to Modern Chess...

No, other than here at Chess Variants, I do not know of any othe websites dedicated to Modern Chess.

>> I mean do people actually play it?

Yes, still in Puerto Rico (where the game was invented in 1968), but not as much anymore.

You can't find Original (brand new) Modern Chess sets anymore.

I got this original (used) Modern Chess set last year while visiting Puerto Rico.

>> 2. It's tempting but I don't like the Bishop adjustment thingy.

It's the only kind of obscure rule, but it was the creator's way of solving the problem of Bishops starting on the same color (which the creator actually didn't see as a problem).

>> Unless perhaps, would giving the Bishop the option to utilise one opportunity per game to move one square in any direction be good?

I guess one can use it as an option or alternative to the original rule. It must agreed before the start of the game to use this variation of the rule.

>> 3. Is it one sided playing an odd number of squares? Does Black or White have a distinct advantage on a 9 x 9 square board?

No. There is no advantage for either player, other than for white having the first move (just like in Orthodox Chess).

>> 4. Where can I buy a 9 x 9 board?

You can try:

Ministers Chess (9x9) at


International Chess Variants Board (10x10, and you make it smaller) at

In Europe you should be able to get other 10x10 International (Polish) Checkers (draughts) boards, which you can customize to 9x9, and use your chess pieces from a couple of Orthodox Chess Sets.

I also found last year a copy of the Spanish version of the game inventor's book in a library of rare books in Spain.

John Smith wrote on 2009-01-01 UTCPoor ★
White has the advantage of a more quickly promoting centre Pawn but it is balanced somewhat by the reverse symmetry. The imbalance between the colours, both in terms of the board and the armies, makes the game ugly, as does the Bishop Adjustment Rule. This is one of the reasons I created Modern Makruk. The most obvious solution would be to include a Marshall, but that would just be another Carrera variant, which may be one of the reasons for the creation of this. I, however, consider the Marshall the lesser of the two evils. Shogi does not suffer from either of these flaws because symmetrical centre Pawn play is disadvantageous for the first player and the Bishops are naturally unbound both by promotion and drops.

Simon Jepps wrote on 2009-01-01 UTCGood ★★★★
I was wondering:

1. Are there any websites dedicated to Modern Chess... I mean do people actually play it?

2. It's tempting but I don't like the Bishop adjustment thingy. Unless perhaps, would giving the Bishop the option to utilise one opportunity per game to move one square in any direction be good?

3. Is it one sided playing an odd number of squares? Does Black or White have a distinct advantage on a 9 x 9 square board?

4. Where can I buy a 9 x 9 board?

George Duke wrote on 2008-08-16 UTC
Here is where all the '9x9's are recently listed at prior comment. So, to add to ones at Coherent are Bifocal, The Travelers, Achernar, Canonical, 9x9 Squares Rotating, Chesquerque, Chancellor, Symmetric Sissa, Nine-Square, Rotary. [Shogi is the only bad 9x9.]

Jose Carrillo wrote on 2008-05-11 UTC
I have developed a more generic Bishop Adjustment Rule for the new Modern Random Chess variation.

My new Bishop Adjustment Rule also applies to Modern Chess:

Jose Carrillo wrote on 2008-04-28 UTC
Can one of the admins for the site update the links at

to include a link to the Modern Chess preset for Game Courier?

The Modern Chess preset's link is:

The 'See Also' page for Modern Chess:

needs also to be updated with the link to the Chess Courier preset above.

Thanks in advance.

George Duke wrote on 2008-04-09 UTC
It is interesting Maura has old tome 'Mathematical Thesis For Modern Chess'. Maura seems to be reacting against 9x9 Chancellor Chess' unbalancing Bishops in keeping them on same colour instead. '9x9' is not that popular size in number of attempts and seems awkward. Yet most games turn out well (better than this Modern) on 9x9. '9x9' must have the highest percentage disproportionately worth 'Excellent' of any particular size-grouping. Who knows why? Maybe because Shogi is so bad from a worldwide perspective, and anything else on 9x9 has to be improvement. Some Excellent CVs on precisely 9x9: Weave & Dungeon, Altair, The Travelers, Coherent, Bifocal, Sissa, Hanga Roa. Good or Very Good CVs on 9x9: Achernar, Kristensen's, Melee, Canonical, 9x9 Squares Rotating, Rotary, Chesquerque, Symmetric Sissa, Three Fat Brothers, Nine-Square. One and all size 9x9 and well worth manufacturing.

Jose Carrillo wrote on 2008-04-06 UTC
Thanks for updating the Modern Chess page with the Bishop Adjustment rule.

I found two typos.

1. The notation for the Bishop and Minister's Knight example is actually
B=MN (I made a mistake before with B=MK).

2. The international organization created that arranged tournaments and
world championships for Modern Chess was FEMDAM. (not FENDAM as Pritchard
incorrently quotes in his book).

FEMDAM = FEderacion Mundial De Ajedrez Moderno

which is Spanish for 'World Federation of Modern Chess'

Can someone please update the two typos in the Modern Chess page?

[All fixed, I think. DH] [Yes. Thanks. JC]

Jose Carrillo wrote on 2008-03-24 UTC
Thanks Antoine!

Can you update the Modern Chess webpage to include the 'Bishop's Adjustment' rule?

Below is my English interpretation of the rule, which appears in Spanish on page 32 of Gabriel Maura's 1973 'Tesis Matematica del Ajedrez Moderno' (Mathematical Thesis for Modern Chess):


The Bishop Adjustment Rule

It consists 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 Minister or Minister's Knight to the left - as long as neither of the pieces being exchanged has been moved from its original square.

The player would have four ways to do the adjustment, but he is only allowed to do it one time throughout the game, if he wishes to. This adjustment counts as a move, just like castling. The notation for it is: B=MN (example for the adjustment with the Minister's Knight).

Antoine Fourrière wrote on 2008-03-24 UTC
Thanks for discovering the bug. I've replaced f8 by #roo.
I don't think there is presently a way for users to upload include files. I guess you can write your functions in the pregame field of your presets for debugging sake and send me include files when you're satisfied with them.

Jose Carrillo wrote on 2008-03-22 UTC
I'm working on the code for two new presets for Chess Courier for randomized variants for Modern Chess:

Modern Random Chess and Modern Fischer Random Chess

I'm trying to reuse some of the code already done for Fischer Random Chess, and found a statement that is too specific in the fischer.txt include file, that prevents this include file to be general enough to be used for 9x9 variants.

In the subroutine to evaluate actual moves by the Black Rook, in the elseif statement there is a reference to a physical coordinate (f8), rather than to a label (#roo):

sub r from to;
  set legal fn R #from #to;
  if not var legal or == old k:
    if == #to #rooo:
      castle #k #kooo #from #rooo;
      set k #kooo;
    elseif == #to f8:
      castle #k #koo #from #roo;
      set k #koo;
  unsetflag #from;

The same is not the case for the subroutine for evaluating actual moves by the White Rook:

sub R from to;
  set legal fn R #from #to;
  if not var legal or == old K:
    if == #to #ROOO:
      castle #K #KOOO #from #ROOO;
      set K #KOOO;
    elseif == #to #ROO:
      castle #K #KOO #from #ROO;
      set K #KOO;
  unsetflag #from;

Here the elseif has a #ROO label that allows this subroutine to be general enough to work for a 9x9 chess variant.

Can someone update the subroutine for black in fischer.txt to have the label #roo instead of f8?

Second question, how do I upload a new file into the include library?

I'm working on the code for a new modern-adjustment.txt file that will be general enough to provide for my new Bishop Adjustment in the randomized versions I'm working on, as well as for the Bishop Commuting found in the modern.txt include file.


Jose Carrillo wrote on 2008-03-16 UTC
BTW. The book confirms the Bishop Castling rule as I've described before. 

The rule is actually called the 'Bishop Adjustment' rule.

In the true nature of Modern Chess, Maura believed the game was better to be played with both Bishops on the dark squares.

But he left the possibility open for players that couldn't let go (of having Bishops in opposite colors).

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