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Chess Variant


XYMYX was created in Ecuador 6 years ago and its main idea is simultaneity, that is, players make their moves at the same time.

In xymyx both players make their moves simultaneously and because of this whoever plays with the white pieces has no advantage, colors practically don't exist. Because of all the knowledge involved in chess, whoever has more experience will have the advantage, but someone who has learned to play xymyx can easily beat an expert chess player because everything is new.


The starting position of orthodox chess.


Same as in orthodox chess. Colors don't exist. There are no white or black pieces. Only of a different color.


All the rules are the same as in orthodox chess, except the following:

To play XYMYX, you only need to know the general rules of Chess and the 4 rules of XYMYX

1. Simultaneity

The players start the game "simultaneously" (ie. the players make their moves at the same time).

2. Two pieces to the same empty square

Because of the simultaneity, two pieces can end up in the same empty square:


a)   If the pieces have different hierarchy, the one with higher hierarchy will stay.

b)   If the pieces have the same hierarchy, the piece of the player who first records the move will stay.

3. Self-capture your own pieces.

In XYMYX you are allowed to capture your own pieces.

 When with a simultaneous move the  pieces of both opponents move to an occupied square, the piece of the player who initially was in the square will stay, maintaining the piece that was moved in the simultaneous play. In this kind of move hierarchy will not govern.

4. Frozen Queen

If a player is checked by the queen, the queen cannot be moved in the following move. The player must move any other piece.


The following notes are not rules but clarifications for some moves that could be confusing.

N1. Checks

The Check must be counteracted -inevitably on the next move- by moving the King to a square where it is not in Check..


a)   Capture the piece which is checking your King

b)   Move one of your own pieces between your King and the checking piece

N2. There are no “Pinned Pieces”.

You can move your pieces even if they are protecting your King.

Why? The King will be in check only in the next move.

N3. Frustrated captures

As a result of the simultaneous move, it is possible that with a move one piece tries to capture another, and at the same time the target piece moves to another square. In this case, no capture will exist. It is important to mention that this rule affects the Pawns as well, which can only capture in cross squares



The following are uncommon and unusual moves:

U1. Simultaneous Checks

It is possible that two Checks happen at the same time.

Check vs. Check. Both players must move their Kings.

Mate vs. Check. The game ends and the winner is the player who has checkmated the opponent

Mate vs. Mate. The player who registers first the move of the Mate wins.

U2. King vs. Pawn

The King could move to f3 because the Pawn only forbids the move to e3 (this square is attacked by the Pawn)

If the Pawn of f4 and the King of e4 moves at the same time to f3, the King will stay and the Pawn will be captured (Rule 2. two pieces to the same empty square)

U3. Pawn Promotion

When the Pawn reaches the eighth rank, it shall be immediately exchanged with a piece of the Pawn's color as a part of the same move, independently from the pieces which remain in the chessboard.

Sample game:

1.Qd1-e2   Ra8-a7

2.Nb1-c3   Ra7-a2

3.Nc3-d5   Ra2-b2

4.Qe2-e7   Rb2-b1

The "bottom" player wins by check mate.

See also