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The Chess Variant Pages

This page is written by the game's inventor, Fergus Duniho.

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Fergus Duniho wrote on 2005-02-17 UTC
Peter, I did have Potential Chess in mind, since I was still living in
Rochester when David created it, and he told me about it. But I don't
remember if we ever actually played it. I'm meaning to elaborate on the
rules of Symposium Chess to fill in the details. Regarding check, here's
what I have in mind. 

When both of a player's Monarchs are checked simultaneously, he must move
to eliminate one or both checks. If he cannot eliminate either check, it is
checkmate. If he eliminates only one check, the one no longer in check then
becomes the King, and the one left in check becomes the Queen. If this is
done by moving one of the Monarchs, it must move as a King, since this is
the Monarch that will become a King. If he can eliminate both checks, such
as by capturing a piece forking the two Monarchs, and this does not involve
moving one Monarch as a Queen, then the two Monarchs remain Monarchs.

If a single Monarch is checked, and it is left in check, then it becomes a
Queen, and the other Monarch becomes King.

If a Monarch is deliberately moved into check, it becomes the Queen, and
the other Monarch becomes King.

It is illegal to make a move that puts both of one's Monarchs into

The general rules are that you cannot do anything with two Monarchs that
you cannot do with a King and Queen, no move may treat a Monarch as though
it were both a King and a Queen, and when any move is legal only under the
assumption that one Monarch is specifically a King or specifically a
Queen, then the two Monarchs immediately differentiate into King and

If Sinister Queens Chess increases White's advantage, then that supports
the importance of bilateral symmetry over diagonal symmetry.

While a leaperless combination of Episcopal Chess and Bigamous Chess might
be closer to Derek's ideal, that was never the goal of this project, which
is merely to create symmetric variants that are as close as possible to
Chess. The idea is to change only one factor, asymmetry to symmetry, and
see whether this is an improvement. Removing the Knights would spoil the
results of any comparison.

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