Commit 7e6054aa authored by Antoni Bella Pérez's avatar Antoni Bella Pérez 🚵🏻
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Add screenshot tags and code cleanup (more readable)

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<chapter id="introduction">
<title>Introduction</title>
<note>
<title>Gametype:</title>
<para>Board</para>
</note>
<note>
<title>Number of possible players:</title>
<para>One or two</para>
</note>
<para>
&i18n-knights; is a chess game. As a player, your goal is to
defeat your opponent by checkmating their king.
</para>
<para>&i18n-knights; is a chess game. As a player, your goal is to
defeat your opponent by checkmating their king.</para>
</chapter>
<chapter id="how-to-play"><title>How to play</title> <!-- do not change this! -->
<!--Describe the objective of the game.-->
<sect1 id="objective">
<title>Objective</title>
<para>Moving your pieces, capture your opponent's pieces until your opponent's king is under attack and they have no move to stop the attack - called <quote>checkmate</quote>.</para>
<para>If it appears you cannot win, you can play for a draw (tie). Move your pieces until you have no legal moves left and your king is not under attack - called <quote>stalemate</quote>.
Other forms of draws can be available depending upon the chess rules being followed for the game.</para>
<para>If it appears you cannot win, you can play for a draw (tie). Move your pieces until you have no legal moves left and your king is not under attack - called <quote>stalemate</quote>. Other forms of draws can be available depending upon the chess rules being followed for the game.</para>
</sect1>
<!--How to play description. Don't be to specific on rules as they have a separate section in this document-->
<sect1 id="starting-the-game">
<title>Starting the Game</title>
<para>
When the program starts or the user selects the <menuchoice><shortcut>
<keycombo action="simul">&Ctrl;<keycap>N</keycap></keycombo> </shortcut>
<guimenu>Game</guimenu> <guimenuitem>New</guimenuitem></menuchoice> menu item,
a dialog is shown. In this dialog, it's possible to
specify who you are playing against, your color and
the time limits.
</para>
<mediaobject><imageobject><imagedata fileref="Knights-newgame-dialog.png" /></imageobject></mediaobject>
<para>
If you wish to play against a friend on the same computer, select
<guilabel>Human (You)</guilabel> for <guilabel>Player 1</guilabel>
and <guilabel>Human</guilabel> for <guilabel>Player 2</guilabel>.
</para>
<para>
If you wish to play against the computer, select
<guilabel>Human (You)</guilabel> for <guilabel>Player 1</guilabel> and
<guilabel>Computer engine:</guilabel> for <guilabel>Player 2</guilabel>.
From this drop down list choose the program you would like to play against, and
make sure that the program you specify is installed on your
computer and that it supports either the XBoard or <acronym>UCI</acronym> protocols.
</para>
<para>
If you have installed a chess engine but it does not appear in the list,
click the <guibutton>Configure...</guibutton> button and add the engine
there. For more information on this dialog see <link linkend="configuration-engines">Computer Engines</link>.
</para>
<note><para>
Even though a program is listed in the dialog, it does not mean it is installed.
Make sure you install whatever chess engine you wish to play against.
You can check whether an engine is installed on your system or not in the
<guilabel>Chess Engines</guilabel> dialog.
</para></note>
<para>
If you wish to play against someone over the Internet,
select <guilabel>Human (You)</guilabel> for <guilabel>Player 1</guilabel> and
<guilabel>Chess server:</guilabel> for <guilabel>Player 2</guilabel>.
You will have to login into the server and find
an opponent before you can start playing.
The Free Internet Chess Server
(<ulink url="https://www.freechess.org/">FreeChess.org</ulink>)
supports guests, but you have to register in order to
play games which affect your rating.
</para>
<para>
You can also watch two programs play against each other, by selecting
<guilabel>Computer engine:</guilabel> for both players.
</para>
<para>
Similarly, you can play a computer engine against an opponent at a chess server.
However, note that the chess server may have a policy regarding such play. For the Free
Internet Chess Server it is located
<ulink url="https://www.freechess.org/Help/HelpFiles/computers.html">here</ulink>.
</para>
<para>
The <guilabel>Use time control</guilabel> check box allows you to turn on an optional
timer. &i18n-knights; uses the standard chess time control which has three parameters
inside spinboxes:
</para>
<para>When the program starts or the user selects the <menuchoice><shortcut>
<keycombo action="simul">&Ctrl;<keycap>N</keycap></keycombo> </shortcut>
<guimenu>Game</guimenu> <guimenuitem>New</guimenuitem></menuchoice> menu item,
a dialog is shown. In this dialog, it's possible to
specify who you are playing against, your color and
the time limits.</para>
<screenshot>
<screeninfo>New Game dialog</screeninfo>
<mediaobject>
<imageobject><imagedata fileref="Knights-newgame-dialog.png" format="PNG" /></imageobject>
<caption>New Game dialog</caption>
</mediaobject>
</screenshot>
<para>If you wish to play against a friend on the same computer, select
<guilabel>Human (You)</guilabel> for <guilabel>Player 1</guilabel>
and <guilabel>Human</guilabel> for <guilabel>Player 2</guilabel>.</para>
<para>If you wish to play against the computer, select
<guilabel>Human (You)</guilabel> for <guilabel>Player 1</guilabel> and
<guilabel>Computer engine:</guilabel> for <guilabel>Player 2</guilabel>.
From this drop down list choose the program you would like to play against, and
make sure that the program you specify is installed on your
computer and that it supports either the XBoard or <acronym>UCI</acronym> protocols.</para>
<para>If you have installed a chess engine but it does not appear in the list,
click the <guibutton>Configure...</guibutton> button and add the engine there.
For more information on this dialog see <link linkend="configuration-engines">Computer Engines</link>.</para>
<note><para>Even though a program is listed in the dialog, it does not mean it
is installed. Make sure you install whatever chess engine you wish to play against.
You can check whether an engine is installed on your system or not in the
<guilabel>Chess Engines</guilabel> dialog.</para></note>
<para>If you wish to play against someone over the Internet, select
<guilabel>Human (You)</guilabel> for <guilabel>Player 1</guilabel> and
<guilabel>Chess server:</guilabel> for <guilabel>Player 2</guilabel>. You will
have to login into the server and find an opponent before you can start playing.
The Free Internet Chess Server (<ulink url="https://www.freechess.org/">FreeChess.org</ulink>)
supports guests, but you have to register in order to play games which affect
your rating.</para>
<para>You can also watch two programs play against each other, by selecting
<guilabel>Computer engine:</guilabel> for both players.</para>
<para>Similarly, you can play a computer engine against an opponent at a chess server.
However, note that the chess server may have a policy regarding such play. For the Free
Internet Chess Server it is located
<ulink url="https://www.freechess.org/Help/HelpFiles/computers.html">here</ulink>.</para>
<para>The <guilabel>Use time control</guilabel> check box allows you to turn on an
optional timer. &i18n-knights; uses the standard chess time control which has three
parameters inside spinboxes:</para>
<itemizedlist>
<listitem><para><guilabel>Time control period:</guilabel> specifies the number of moves
after which the <guilabel>Initial time limit:</guilabel> is added to the player's clock.
you can disable this addition by setting the value to zero.</para>
<note><para>
This option is not available when playing on a chess server.
</para></note>
<para/></listitem>
<note><para>This option is not available when playing on a chess server.</para></note><para/></listitem>
<listitem><para>The <guilabel>Initial time limit:</guilabel> is the amount of time the
players start with.</para></listitem>
<listitem><para><guilabel>Increment per move:</guilabel> specifies how much time will be
......@@ -150,507 +145,572 @@
disable incrementing the clock.</para></listitem>
</itemizedlist>
<para>
After you press the <guibutton>OK</guibutton> button, the dialog will close.
If you selected a player at a chess server, you will have to log in and find your opponent.
Otherwise, the game will start immediately.
</para>
<note><para>
&i18n-knights; will load a default theme automatically once
you start the game and you can begin playing right away.
</para></note>
<para>After you press the <guibutton>OK</guibutton> button, the dialog will close. If you
selected a player at a chess server, you will have to log in and find your opponent.
Otherwise, the game will start immediately.</para>
<note><para>&i18n-knights; will load a default theme automatically once you start the game
and you can begin playing right away.</para></note>
</sect1>
<sect1 id="server-dialog">
<title>The Chess Server Dialog</title>
<mediaobject><imageobject><imagedata fileref="Knights-server-account.png" /></imageobject></mediaobject>
<para>
If you chose to play on a chess server, you must first log in to the server.
If you have an account at the server, type in your username and password, and
select the <guilabel>This is a registered account</guilabel> check box.
Otherwise, type in a username of your choice, and press the <guibutton>Log in</guibutton> button.
</para>
<para>
There are two ways to choose the opponent. Either you post an ad for your game
(called a <quote>seek</quote>), or you respond to someone else's seek.
</para>
<mediaobject><imageobject><imagedata fileref="Knights-server-challenges.png" /></imageobject></mediaobject>
<para>
To post your own, go to the <guilabel>Challenges</guilabel> tab and press
<guibutton>Seek</guibutton> button. If you checked
<guilabel>Automatically start the game</guilabel>, once a player has accepted
your seek, the game will start immediately.
Otherwise, you have to accept the challenge manually,
by selecting it from the list and press <guibutton>Accept</guibutton> button.
</para>
<mediaobject><imageobject><imagedata fileref="Knights-server-list.png" /></imageobject></mediaobject>
<para>
To respond to other people's seeks, use the <guilabel>Seek List</guilabel>
or <guilabel>Seek Graph</guilabel> tabs. On either tab, select the seek by clicking on it
and then pressing the <guibutton>Accept</guibutton> button.
</para>
<mediaobject><imageobject><imagedata fileref="Knights-server-graph.png" /></imageobject></mediaobject>
<para>
The seek graph displays all currently posted seeks, arranged by opponent's rating
and game duration. Clicking on a point on the graph accepts the seek.
</para>
<note><para>
For advanced usage, &i18n-knights; provides direct access to the server console.
Select the <guilabel>Console</guilabel> tab to use it.
</para></note>
<screenshot>
<screeninfo>Chess Server dialog</screeninfo>
<mediaobject>
<imageobject><imagedata fileref="Knights-server-account.png" format="PNG" /></imageobject>
<caption>Account tab</caption>
</mediaobject>
</screenshot>
<para>If you chose to play on a chess server, you must first log in to the server.
If you have an account at the server, type in your username and password, and
select the <guilabel>This is a registered account</guilabel> check box. Otherwise,
type in a username of your choice, and press the <guibutton>Log in</guibutton> button.</para>
<para>There are two ways to choose the opponent. Either you post an ad for your game
(called a <quote>seek</quote>), or you respond to someone else's seek.</para>
<screenshot>
<screeninfo>Chess Server dialog</screeninfo>
<mediaobject>
<imageobject><imagedata fileref="Knights-server-challenges.png" format="PNG" /></imageobject>
<caption>Challenges tab</caption>
</mediaobject>
</screenshot>
<para>To post your own, go to the <guilabel>Challenges</guilabel> tab and press
<guibutton>Seek</guibutton> button. If you checked <guilabel>Automatically start the game</guilabel>,
once a player has accepted your seek, the game will start immediately. Otherwise, you
have to accept the challenge manually, by selecting it from the list and press
<guibutton>Accept</guibutton> button.</para>
<screenshot>
<screeninfo>Chess Server dialog</screeninfo>
<mediaobject>
<imageobject><imagedata fileref="Knights-server-list.png" format="PNG" /></imageobject>
<caption>Seek List tab</caption>
</mediaobject>
</screenshot>
<para>To respond to other people's seeks, use the <guilabel>Seek List</guilabel> or
<guilabel>Seek Graph</guilabel> tabs. On either tab, select the seek by clicking on it
and then pressing the <guibutton>Accept</guibutton> button.</para>
<screenshot>
<screeninfo>Chess Server dialog</screeninfo>
<mediaobject>
<imageobject><imagedata fileref="Knights-server-graph.png" format="PNG" /></imageobject>
<caption>Seek Graph tab</caption>
</mediaobject>
</screenshot>
<para>The seek graph displays all currently posted seeks, arranged by opponent's rating
and game duration. Clicking on a point on the graph accepts the seek.</para>
<note><para>For advanced usage, &i18n-knights; provides direct access to the server console.
Select the <guilabel>Console</guilabel> tab to use it.</para></note>
</sect1>
<sect1 id="playing-the-game">
<title>Playing the Game</title>
<para>
Pieces are moved by clicking on them and dragging them to
the desired spot. You can only move a piece if it's yours,
it's your turn, and moving that piece does not put
your king into immediate danger.
</para>
<para>
&i18n-knights; follows the rules of standard chess, so you cannot make an illegal move.
</para>
<para>Pieces are moved by clicking on them and dragging them to the desired spot.
You can only move a piece if it's yours, it's your turn, and moving that piece
does not put your king into immediate danger.</para>
<para>&i18n-knights; follows the rules of standard chess, so you cannot make an illegal move.</para>
</sect1>
</chapter>
<chapter id="rules_and_tips">
<title>Game Rules, Strategies and Tips</title> <!-- do not change this! -->
<!--This section has to do with game rules. Please give a detailed description of those using lists or paragraphs.-->
<sect1 id="standard-rules">
<title>Standard Rules</title>
<para>The main set of rules for chess are set by the World Chess Federation - FIDE. Other national and local groups
may make slight modifications to the rules. Usually the major differences between rules are about timekeeping or types of
draws allowed - the basic game and piece movement are the same. &i18n-knights; supports standard chess and has some timing flexibility.</para>
<para>There are many variants to standard chess. One source has found over 2000 different variants of the game. Major
variants include Fischer Random, Bughouse, Crazyhouse and Suicide. Variants have differing rules on piece capture, piece
movement, ending the game and returning pieces to play. &i18n-knights; does not support chess variants.</para>
<para>Complete rules of standard chess can be found at:</para>
<itemizedlist>
<listitem><para>World Chess Federation-FIDE (<ulink url="https://www.fide.com/">fide.com</ulink>)</para></listitem>
<listitem><para>United States Chess Federation-USCF (<ulink url="https://new.uschess.org/">new.uschess.org</ulink>)</para></listitem>
</itemizedlist>
<para>Rules and general chess information can be found at:</para>
<itemizedlist>
<listitem><para><ulink url="https://en.wikipedia.org/wiki/Rules_of_chess">Wikipedia</ulink>&nbsp;</para></listitem>
</itemizedlist>
</sect1>
<sect1 id="board">
<title>Chessboard</title>
<sect2 id="board-layout">
<title>Board Layout</title>
<para>A chessboard consists of 64 equal squares arranged in eight rows and eight columns. The squares are arranged in
two alternating colors, white and black. Many different materials are used to make chessboards, so the lighter
colored material is known as white and the darker material is known as black.</para>
<para>Parts of the board are known by special names:</para>
<itemizedlist>
<listitem><para>Rank - the eight horizontal rows of the chess board are called ranks.</para></listitem>
<listitem><para>File - the eight vertical columns of the chess board are called files.</para></listitem>
<listitem><para>Diagonal - a straight line of squares of the same color running at an angle from
one edge of the board to another edge is called a diagonal.</para></listitem>
<listitem><para>Center - the four squares found in the middle of the board are called the center.</para></listitem>
</itemizedlist>
<para>Each individual square has a name so records of the moves of the game can be kept. Several naming systems exist,
but <quote>algebraic notation</quote> is the most popular and is the official system. In this system, each square is
named for the row and column in which it is found. The ranks (rows) are numbered from 1 to 8 beginning with white's
side of the board and moving to black's side of the board. The files (columns) are labeled by lower case letters from
a to h moving from left to right based on the white player's viewpoint. The square is named by the letter followed by
the number. Thus the lower left hand square is known as a1. The naming structure can be seen in the following
diagram:</para>
<mediaobject><imageobject><imagedata fileref="Knights-board.png" /></imageobject></mediaobject>
</sect2>
<sect2 id="board-setup">
<title>Initial Setup</title>
<para>The chessboard is rotated so that there is a white square in the first row at the player's right side.</para>
<para>The pieces are placed on the white and black side of the board in the same manner. In the first row beginning
at both outer edges and moving inward, place the rook (sometimes called the castle), the knight (sometimes called
the horse) and the bishop. For the two remaining squares, place the queen on the square with the same color. Place
the king on the final square. When completed, the same pieces face each other across the board. On the second row
place a row of pawns. The finished board then looks like the diagram below.</para>
<mediaobject><imageobject><imagedata fileref="Knights-board-setup.png" /></imageobject></mediaobject>
</sect2>
</sect1>
<sect1 id="piece-movement">
<title>Piece Movement</title>
<sect2 id="all-movement">
<title>Moving and Capturing</title>
<para>Chess has six types of pieces: the Pawn, Rook, Knight, Bishop, Queen and King. Each piece has its own
unique way to move. There are some similarities between the moves of the various pieces. All the pieces
except the knight move in a straight line - horizontally, vertically or diagonally. They cannot move past the
end of the board and return on the other side. The edge of the board is a boundary which cannot be crossed.
All the pieces except the knight may not jump over other pieces - all squares between the square where the piece
starts its move and where it ends its move must be empty. The move may not end on a square presently occupied
by a piece of the same color.</para>
<para>If the square where a piece ends its move contains an opponent's piece, the opponent's piece is <quote>captured</quote>,
and it is removed from play. All the pieces may be captured except the king. The game ends on the move before the
king is captured - <quote><link linkend="checkmate">checkmate</link></quote>. Capturing always requires the attacking piece
to land on the square of the opponent's piece while making a normal move. The only exception is for capturing a pawn
<link linkend="en_passant-movement">en passant</link>. You are not required to capture a piece when there is an opportunity
to do so, capturing is an option. The only time that capture is required is if the king is under attack and capturing the
attacking piece is the only way to stop the attack.</para>
<para>In the picture below, the white rook can move to the right, left, up or down (vertically or horizontally) in straight lines.
It can move down and to the right any number of squares until the end of the board is reached. These squares have a green
X on them. It can move a maximum of two squares to the left. The remainder of the board is blocked by a piece of the same
color, in this case a white knight. The rook cannot jump over the knight to reach the end of the board. It can move only one square
up before being blocked by the black pawn. It can capture the pawn by moving two squares up and landing on the pawn, since the
pawn is an opposing piece (piece of a different color). This square has a red X on it. It cannot jump over the pawn to reach
the end of the board. Therefore, the rook has a total of ten squares where it can go.</para>
<mediaobject><imageobject><imagedata fileref="Knights-move-limits.png" /></imageobject></mediaobject>
<para>To begin the game, white moves first. The players then alternate making one move at a time. You must move on your turn, you are not allowed to pass.</para>
</sect2>
<sect2 id="pawn-movement">
<title>Pawn</title>
<para>The pawn is the most numerous and the least powerful piece on the chessboard. Pawns are unusual in their movement. Generally
the pawn moves forward only, one square at a time. An exception is the first time a pawn is moved, it may move forward two squares.
The pawn cannot jump over other pieces; any piece directly in front of a pawn blocks its advance to that square. The pawn is the
only piece that cannot move backward. The pawn is also the only piece that does not capture in the same way that it moves. The
pawn captures an opposing piece by moving diagonally one square - it cannot capture by moving straight ahead.</para>
<para>In the picture below the lower pawn is still on its original square, so it may move one or two squares forward (indicated
by the green X). It may capture by moving to the right or left at a diagonal, but only if that square is occupied by an opposing
piece (indicated by the red X). Otherwise, it may not move diagonally. The upper pawn has already moved from its original square.
It may move only one square forward. Likewise, it can capture moving to the left or right diagonally if the square contains an
opposing piece.</para>
<mediaobject><imageobject><imagedata fileref="Knights-move-pawn.png" /></imageobject></mediaobject>
<para>The pawn also is involved in two special moves. The first is the <link linkend="en_passant-movement">en passant capture</link>
where a pawn is captured on its initial two square move. The second is the <link linkend="pawn-promotion-movement">pawn promotion</link>
where a pawn is promoted to another piece when the pawn reaches the other end of the board.</para>
</sect2>
<sect2 id="bishop-movement">
<title>Bishop</title>
<para>The Bishop moves in a straight line diagonally on the board. It can move as many squares as wanted, until it meets the end of
the board or another piece. The bishop cannot jump over other pieces. The bishop captures on the same path it moves, by landing
on the square of the opposing piece. Because of the way the bishop moves, the piece always remains on the same color squares it
started on. Each player begins with two bishops, one on the black-colored and one on the white-colored squares. They are frequently
referred to as the <quote>dark-squared</quote> bishop and <quote>light-squared</quote> bishop. The bishops can also be named according
to the side they begin on - king's bishop and queen's bishop.</para>
<mediaobject><imageobject><imagedata fileref="Knights-move-bishop.png" /></imageobject></mediaobject>
</sect2>
<sect2 id="rook-movement">
<title>Rook</title>
<para>The rook moves in a straight line either horizontally or vertically through any number of unoccupied squares, until it reaches
the end of board or it is blocked by another piece. It cannot jump over other pieces. The rook captures on the same path
it moves, by occupying the square on which an enemy piece stands. The rook can land on any square on the board, therefore it
is one of the more powerful pieces on the board.</para>
<mediaobject><imageobject><imagedata fileref="Knights-move-rook.png" /></imageobject></mediaobject>
<para>The rook is also involved in a special move. It is the <link linkend="castling-movement">castling move</link>
where a rook and the king are grouped into a defensive position.</para>
</sect2>
<sect2 id="knight-movement">
<title>Knight</title>
<para>The Knight is the most special piece in chess, having a flexibility that makes it a powerful piece. The knight is the
only piece on the board that may jump over other pieces. The knight moves two squares horizontally or vertically and
then one more square at a right-angle. The knight’s move is shaped as an <quote>L</quote>. The knight always lands on a square
opposite in color from its initial square. The knight can jump over pieces of either color while going to its
destination square, but it does not capture any pieces it jumps over. The knight captures by landing on the square
of the opposing piece. The knight cannot land on a square occupied by a piece of the same color. Since the knight's
movement is not in a straight line, it can attack a queen, bishop, or rook without being reciprocally attacked by that
piece.</para>
<mediaobject><imageobject><imagedata fileref="Knights-move-knight.png" /></imageobject></mediaobject>
</sect2>
<sect2 id="queen-movement">
<title>Queen</title>
<para>The Queen is considered the most powerful piece on the board. It can move any number of squares in a straight
line - either vertically, horizontally or diagonally. The queen moves like the rook and bishop combined. Unless
capturing, the queen must move to an unoccupied square; and it cannot jump over pieces. The queen captures on the
same path it moves, by landing on the square of the opposing piece.</para>
<mediaobject><imageobject><imagedata fileref="Knights-move-queen.png" /></imageobject></mediaobject>
</sect2>
<sect2 id="king-movement">
<title>King</title>
<para>The King is the most important piece in chess. If the king is trapped so that its capture is unavoidable, the game is
over and that player loses. The king has little mobility, so it is also considered one of the weakest pieces in the game.
The king can move to any adjacent square. That is, it can move one square in any direction: horizontally, vertically, or
diagonally. It cannot move onto a square occupied by a piece of the same color. The king captures another piece in
the same way it moves, by landing on the square of the opposing piece. There is an additional limit on the movement of
the king. The king may not move to a square which would put the king under attack by an opposing piece (called in <quote>check</quote>).
As a result of this limit, two kings may never stand next to each other - since moving next to the opposing king would
put the moving king into check. The king can also be forced to move or capture if the king is under attack
(<quote>check</quote>) and the only way to stop the attack is to move the king.</para>
<mediaobject><imageobject><imagedata fileref="Knights-move-king.png" /></imageobject></mediaobject>
</sect2>
</sect1>
<sect1 id="special-movement">
<title>Special Moves</title>
<sect2 id="en_passant-movement">
<title>En Passant</title>
<para>When the rule to allow a pawn to move two squares on its first move was added, a pawn could potentially evade capture by an
opponent's pawn by going past a square under attack. The en passant capture (from the French for <quote>in passing</quote>) was
added to prevent this. The capture is made exactly as if the pawn had moved only one square forward. There are
special conditions for the en passant capture:</para>
<itemizedlist>
<listitem><para>A pawn must move two squares from its initial position in a single move.</para></listitem>
<listitem><para>An opposing pawn must be attacking the square the first pawn moved over.</para></listitem>
<listitem><para>The first pawn can be captured as if it moved only one square.</para></listitem>
<listitem><para>The capture can only be made at the opponent's next move. If the capture is not made,
the first pawn is safe from en passant capture for the remainder of the game.</para></listitem>
</itemizedlist>
<para>In the diagram below, the white pawn has not moved from its initial position. Its first move can be
one or two squares ahead. The first square is under attack by the black pawn (pawns attack diagonally) as
indicated by the red X. The white pawn moves ahead two squares, avoiding the attack. On the next move,
the black pawn moves into the square where the white pawn would have moved if it could only move a single
square on the first move. The black pawn successfully attacks the white pawn, and captures it
<quote>en passant</quote>. The white pawn is removed from play.</para>
<mediaobject><imageobject><imagedata fileref="Knights-enpassant.png" /></imageobject></mediaobject>
</sect2>
<sect2 id="castling-movement">
<title>Castling</title>
<para>Castling uses the king and one rook, and is the only time in a game when more than one piece may be moved
during a single turn. In castling a king is moved two squares towards the rook and the rook is then moved to
the square on the other side of the king.</para>
<para>Castling has some rigid requirements:</para>
<itemizedlist>
<listitem><para>Both the king and the rook may never have moved during the game.</para></listitem>
<listitem><para>There are no pieces between the king and the rook.</para></listitem>
<listitem><para>The king is not in check.</para></listitem>
<listitem><para>The king does not cross over a square that is attacked by the opponent's pieces.</para></listitem>
<listitem><para>The king does not end the move on a square that is attacked by the opponent's pieces. (The
castling move cannot end with the king in check.)</para></listitem>
</itemizedlist>
<para>There are two forms of castling. One is called <quote>kingside castling</quote>. It is also known as
<quote>short castling</quote>, since it is performed to the short side of the board and the rook only has to
move two squares to the opposite side of the king. It is diagramed below:</para>
<mediaobject><imageobject><imagedata fileref="Knights-castle-kingside.png" /></imageobject></mediaobject>
<para>The second form of castling is called <quote>queenside castling</quote>, where the king moves towards the
square vacated by the queen. It is also known as <quote>long castling</quote>, since it is performed to the long
side of the board and the rook has to move three squares to the opposite side of the king. It is diagramed below:</para>
<mediaobject><imageobject><imagedata fileref="Knights-castle-queenside.png" /></imageobject></mediaobject>
<note><para>
In &i18n-knights; to castle you move the king two squares towards the rook. &i18n-knights; will complete
the castling move. Do not move the rook, as &i18n-knights; assumes you wish only to move the rook and
not to castle.
</para></note>
</sect2>
<sect2 id="pawn-promotion-movement">
<title>Pawn Promotion</title>
<para>When a pawn has reached the other end of the board it cannot move further, since
it always must move forward and not backwards. The pawn is then turned
(<quote>promoted</quote>) into a queen, rook, bishop or knight. This promotion
occurs as part of the move. Usually the piece chosen is the queen, often called
<quote>queening</quote>. The other pieces are sometimes chosen when their movements
will aid in checkmate, often called <quote>under promoting</quote>. The pawn can be
turned into a piece even if that type of piece is still on the board. Thus you can have
two queens or three rooks, bishops or knights in play at once.</para>
</sect2>
</sect1>
<sect1 id="game-end">
<title>Game Endings</title>
<sect2 id="checkmate">
<title>Checkmate</title>
<para>When a king is under attack and threatened with capture by an opponent's piece, the king is
said to be <quote>in check</quote>. A king must get out of check immediately. There are three possible
ways to get out of check.</para>
<itemizedlist>
<listitem><para>Capture the attacking piece.</para></listitem>
<listitem><para>Move the king away from the attack and to a safe square which is not under attack by
an opponent's piece.</para></listitem>
<listitem><para>Block the attack by placing a piece between the attacker and the king.
(Cannot be done for an attack by a knight or pawn.)</para></listitem>
</itemizedlist>
<para>
If the king has no way to escape from the check, the position is called <quote>checkmate</quote> and
the game ends. The player who is checkmated loses the game. The king is never actually captured
and removed from the board.</para>
</sect2>
<sect2 id="resign">
<title>Resign</title>
<para>At any time during the game, a player may resign (quit). The
game ends and the player's opponent wins the game.</para>
</sect2>
<sect2 id="draw">
<title>Draw</title>
<para>A <quote>draw</quote> is a tie between the players. There are several ways that a
draw can occur.</para>
<sect1 id="standard-rules">
<title>Standard Rules</title>
<para>The main set of rules for chess are set by the World Chess Federation - FIDE. Other national and local groups
may make slight modifications to the rules. Usually the major differences between rules are about timekeeping or types of
draws allowed - the basic game and piece movement are the same. &i18n-knights; supports standard chess and has some timing
flexibility.</para>
<para>There are many variants to standard chess. One source has found over 2000 different variants of the game. Major
variants include Fischer Random, Bughouse, Crazyhouse and Suicide. Variants have differing rules on piece capture, piece
movement, ending the game and returning pieces to play. &i18n-knights; does not support chess variants.</para>
<para>Complete rules of standard chess can be found at:</para>
<itemizedlist>
<listitem><para>Stalemate - (see below)</para></listitem>
<listitem><para>Threefold repetition - If the exact same position is repeated at least 3 times
(not necessarily by a repetition of moves). It requires that the possible moves of all
the pieces of both players are the same. If the possibility of a pawn being captured
en passant has changed or the possibility to castle has changed, the position is not
the same - even if the pieces are in the same locations.</para></listitem>
<listitem><para>Fifty-move rule - If no piece has been captured or a pawn moved in the last fifty moves
by each player.</para></listitem>
<listitem><para>Impossibility of checkmate - If a position arises in which neither player could possibly
give checkmate by a series of legal moves. Usually this is because there is insufficient material left
to checkmate, but it is possible in other positions. Combinations with insufficient material to
checkmate are:</para>
<itemizedlist>
<listitem><para>king versus king</para></listitem>
<listitem><para>king and bishop versus king</para></listitem>
<listitem><para>king and knight versus king</para></listitem>
<listitem><para>king and bishop versus king and bishop with both bishops on the same color</para></listitem>
</itemizedlist>
</listitem>
<listitem><para>Time expires - If a player's time runs out and their opponent does not have mating material.
(see below)</para></listitem>
<listitem><para>Mutual agreement - If both players agree to draw.</para></listitem>
<listitem><para>World Chess Federation-FIDE (<ulink url="https://www.fide.com/">fide.com</ulink>)</para></listitem>
<listitem><para>United States Chess Federation-USCF (<ulink url="https://new.uschess.org/">new.uschess.org</ulink>)</para></listitem>
</itemizedlist>
</sect2>
<sect2 id="stalemate">
<title>Stalemate</title>
<para>If a player has no legal move (every possible move would put their king in check) but
their king is not presently in check, the game ends in a <quote>stalemate</quote>. Stalemate results in
the game being a draw.</para>
</sect2>
<sect2 id="time-end">
<title>Time</title>
<para>If time should run out on a player before they complete the
required number of moves:</para>
<para>Rules and general chess information can be found at:</para>
<itemizedlist>
<listitem><para>The player loses the game if the opponent has mating material.</para></listitem>
<listitem><para>The game is a draw if the opponent does not having mating material.</para></listitem>
<listitem><para><ulink url="https://en.wikipedia.org/wiki/Rules_of_chess">Wikipedia</ulink>&nbsp;</para></listitem>
</itemizedlist>
<para>Mating material is considered to be any group of pieces except just a king, a king and a bishop,
or a king and a knight.</para>
</sect2>
</sect1>
<sect1 id="time-controls">
<title>Time Controls</title>
<