A Game Courier Preset for Extra Move Chess

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Extra Move Chess

Rules enforced. Legal moves displayed.

Welcome to Game Courier, where you can play Extra Move Chess and many other Chess variants through online correspondence.

Rules of Extra Move Chess

King

Queen

Rook

Bishop

Knight

Pawn

Extra Move Chess is played like Chess except as follows:

1. With the exception of White's first turn, you get to move twice each turn.
2. The second move is optional and is subject to the following conditions:
1. You may not move the piece you just moved.
2. You may not capture a piece.
3. You may move an unmoved Pawn two spaces forward only on your second move or on the first move of White's first turn.
4. You are checkmated if your King is in check at the beginning of your turn, and you cannot get out of check in one move, or, which is effectively the same, if your King is in check at the beginning of your second move.
5. You are stalemated if you have no moves available at the beginning of your turn; being unable to make the second move of your turn is not stalemate.

Notation

You should be aware that Game Courier's notation is not identical with standard Chess notation. Game Courier has been designed for general use with any of several different Chess variants, and it accordingly uses a generic system of notation. This system is described in detail in the User's Guide. Here are the basics you need to know for Extra Move Chess. Move a piece by writing its present coordinate, a hyphen, and its destination coordinate. For example, "e2-e4". There is no special operator for captures. A hyphen should be used even when a piece is captured. To signal to your opponent what piece you moved, and to provide an extra bit of error checking on the move you enter, you may include Game Courier's notation for the piece before the move. For example, "P e2-e4". Note that Game Courier uses uppercase letters for White pieces and lowercase for Black pieces. Black could enter "p e7-e5" for a move but not "P e7-e5". Write two moves by separating them with a semicolon, such as "N b1-c3; P d2-d3".

Most moves must be written explicitly. Game Courier does not rely on context to understand ambiguously written moves, such as "e4", which makes sense only when one piece can move there. Promotion should be handled by explicitly adding the promoted piece to the space the Pawn has moved to. For example, "P f7-f8; Q-f8" would move a White Pawn from f7 to f8 and promote it to a White Queen. Each promotion should immediately follow the move of the Pawn being promoted. For example, "P f7-f8; Q-f8; g7-g8; Q-g8" but not "P f7-f8; g7-g8; Q-f8; Q-g8".

Because this preset is automated to enforce rules and handle special moves, it allows slightly abbreviated expressions for en passant and castling. En passant should be entered as a move by your Pawn. For example, "P e5-f4" would capture by en passant a Black Pawn that had just made a double move to f5. When receiving a move like this, this preset will check whether it is a legal en passant move, and if it is, it will automatically capture the enemy Pawn. Castling should be entered as a move by your King. Just move your King where it would go in the castling move. The preset will then check whether castling to that space is legal, and if it is, it will automatically move the Rook to the space the King passed over.

How to Move Pieces

Full Algebraic Notation

Algebraic notation identifies each space by a coordinate that begins with its file label and ends with its rank label. On the Chess board, files go up and down from one player to the other, and ranks go from left to right. In most games, files are represented by letters, and ranks are represented by numbers, but there is no fixed rule requiring this for all games, and some games, such as Shogi, reverse this convention. If you look at the diagram, you will usually see the file labels going from left to right and the file labels going up and down. And if you hover your mouse over a space, you will normally see the name of the coordinate appear in a tooltip.

It is not uncommon to see algebraic notation being used for Chess, but it is often in an abbreviated format that requires you to know both the rules of the game and the current position to know exactly which piece moves where. For example, the notation "Ne6" indicates that a Knight is moving to e6, but it doesn't indicate which Knight, and it doesn't specify where the Knight is coming from. To figure this out, you need to know how a Knight moves and which Knight on the board can make a legal move to e6.

Although rules may be programmed for individual games, Game Courier itself does not know the rules of any game, and it is unable to parse abbreviated algebraic notation. Therefore, it relies on full algebraic notation, which completely specifies the move without requiring any knowledge of the game's rules or the current position. The most usual type of full algebraic notation indicates the piece that is moving by its label, the space it is moving from, and the space it moving to. In Chess, a typical first move might be written as "P e2-e4". When you hover your mouse over a piece, you will normally see the piece label followed by the coordinate for the space, and when you hover it over an empty space, you will normally see the coordinate label. Including the piece label in your notation allows Game Courier to check that the piece you're moving is the right one, and it makes game notation easier to follow, but it is not mandatory.

You may promote a piece by including a promotion move after your regular move. A promotion move has a piece go directly to a coordinate. Here is an example: "p e7-e8; q-e8".

You may remove a piece from a space by adding an @ to the space or by omitting the destination coordinate. For example, both "@-e4" and "e4-" would remove the piece on "e4". This is useful for en passant when you are playing a game that does not handle this automatically. For example, "P d5-e6; e5-" removes the Pawn on e5 after a Pawn moves from d5 to e6.

You will not need to remove spaces for most games, but if you should need to, you can do this by omitting the first coordinate in a move. For example, "-e4" would remove e4 from the board. To add or return a space to the board, you may add an @ or any other piece to it.

Available Pieces

Pieces are represented by labels, usually using uppercase letters for White and lowercase letter for Black. When you enter a move or specify the starting position for a game, you should remember that piece labels are case-sensitive. Many piece sets are available for use with Game Courier, and this table shows you which pieces belong to the piece set you are currently using.

These pieces come from a set containing more pieces, but this preset has had the set of pieces reduced to those used in the game.

Credits

This preset uses the Abstract settings file for Extra Move Chess, which was made by Fergus Duniho.

Game Courier was created, programmed and written by Fergus Duniho.

Game Courier, Copyright © Fergus Duniho, 2001-2017