Overview
The game is a turn based two-player game, and each player is represented by a set of pieces, being black or white, 16 pieces in all:

• One king
• One queen
• Two rooks
• Two bishops
• Two knights
• Eight pawns

The game is played on a chessboard, consisting of 64 squares: eight rows (1-8) and eight columns (a-h). The squares are alternately light (white) and dark (black).

Players take turns in moving one piece at a time. White player always starts the game (the player that plays with the white pieces). A move consists of moving one of the pieces of the player to a different square, following the rules of movement for that piece - there is one special exception, named castling, where players move two pieces simultaneously.

A player can take a piece of the opponent by moving one of his own pieces to the square that contains a piece of the opponent. The opponent's piece is then removed from the board, and is out of play for the rest of the game. Beware that taking is not compulsory!

The board is set up in the following way: At the second row there are eight white pawns, at the seventh row there are eight black pawns. At the first row, from left to right, we have a: rook, knight, bishop, queen, king, bishop, knight, and rook. Note that the queens start on squares of their own color, with a dark square in each player's left hand corner.

Movement of the pieces
To make a move, the player must drag a piece to another square. Once the player has picked up the piece, a marker piece will appear below legal squares this piece is being dragged over. If the piece is dropped on an illegal square it is being snapped back to the square it originally came from. All piece types have different movement patterns, which are the following:

Rook
The rook moves in a straight line, horizontally or vertically. The rook may not jump over other pieces, that is: all squares between the square where the rook starts its move and where the rook ends its move must be empty. (As for all pieces, when the square where the rook ends his move contains a piece of the opponent, then this piece is taken. The square where the rook ends his move may not contain a piece of the player owning this rook.)

Bishop
The bishop moves in a straight diagonal line. The bishop may also not jump over other pieces.

Queen
The queen has the combined moves of the rook and the bishop, i.e., the queen may move in any straight line, horizontal, vertical, or diagonal.

Knight
The knight makes a move that consists of first one step in a horizontal or vertical direction, and then one step diagonally in an outward direction. The knight jumps: it is allowed that the first square that the knight passes over is occupied by an arbitrary piece. For instance, white can start the game by moving his knight from b1 to c3. The knight does further not affect the piece that is jumped over. As usual, a knight takes a piece of the opponent by moving to the square that contains that piece.

Pawn
The pawn moves differently regarding whether it moves to an empty square or whether it takes a piece of the opponent. When a pawn does not take, it moves one square straight forward. When this pawn has not moved at all, i.e., the pawn is still at the second row (from the owning players view), the pawn may make a double step straight forward. For instance, a white pawn on d2 can be moved to d4.

When taking, the pawn goes one square diagonally forward.

There is one special rule, called taking en-passant. When a pawn makes a double step from the second row to the fourth row, and there is an enemy pawn on an adjacent square on the fourth row, then this enemy pawn in the next move may move diagonally to the square that was passed over by the double-stepping pawn, which is on the third row. In this same move, the double-stepping pawn is taken. This taking en-passant must be done directly: if the player who could take en-passant does not do this in the first move after the double step, this pawn cannot be taken anymore by an en-passant move. This special rule can be optionally enabled or disabled in the settings dialog of the matchmaking lobby (it is enabled by default).

Pawns that reach the last row of the board are promoted. When a player moves a pawn to the last row of the board, he replaces the pawn with a queen, rook, knight, or bishop (of the same color). Usually, players will promote the pawn to a queen, but the other types of pieces are also allowed. It is not required that the pawn is promoted to a piece that was taken earlier. Thus, it is for instance possible that a player has at a certain moment two or more queens.

King
The king moves one square in any direction, horizontally, vertically, or diagonally. There is one special type of move, made by a king and rook simultaneously, called castling: see below.

The king is the most important piece of the game, and moves must be made in such a way that the king is never in check: see below.

Castling
The following conditions must be met for a castling move to be considered legal:

• The king that makes the castling move has not yet moved in the game.
• The rook that makes the castling move has not yet moved in the game.
• The king is not in check.
• The king does not move over a square that is attacked by an enemy piece during the castling move, i.e., when castling, there may not be an enemy piece that can move (in case of pawns: by diagonal movement) to a square that is moved over by the king.
• The king does not move to a square that is attacked by an enemy piece during the castling move, i.e., you may not castle and end the move with the king in check.
• All squares between the rook and king before the castling move are empty.

Check
When the king of a player can be taken by a piece of the opponent, one says that the king is in check. For in-stance, the white player moves his rook to a position such that it attacks the black king, i.e., if black doesn't do anything about it, the rook could take the black king in the next move: we say that the white rook gives check. It is considered good manners to say check when one checks ones opponent (this can be optionally selected in the settings dialog of the matchmaking lobby).

It is not allowed to make a move that will leave ones king is in check after the move. If a player accidentally tries to make such a move, he will be warned of this and the king will revert to its original position automatically. If check warnings have been disabled in the matchmaking lobby, making this move is legal, but will still result in a loss.

Mate
When a player is in check, and he cannot make a move such that after the move, the king is not in check, then he is mated. The player that is mated lost the game, and the player that mated him won the game (gaining 1 point).

Note that there are three different possible ways to remove a check:

• Move the king away to a square where he is not in check.
• Take the piece that gives the check.
• Move a piece between the checking piece and the king (in case of a check, given by a rook, bishop or queen).

Stalemate
When a player cannot make any legal move, but he is not in check, then the player is stalemated. In a case of a stalemate, the game is a draw.
Other rules:
There are a number of different ways in which a game can end

Resign
A player can resign the game, which means that he has lost and his opponent has won.

Draw proposal
A player can propose a draw during his own turn, which will be sent as soon as the player has sent his move. His opponent can then accept the proposal (in which case the game ends and is a draw) or refuse the proposal (in which case the game continues).

Dead position
If at any time in the game neither of the players can cause a checkmate, using any series of legal moves, the game will end in a draw, provided the move leading to this situation was legal.

50 move rule
This rule states that if a game has 50 consecutive moves by each player without a pawn being moved or a piece being captured, the game will end in a draw.

3 identical boards rule
If at any time during the game the exact same board layout (exact same pieces in the exact same squares) occurs for the third time, the game ends in a draw.

Timers
The game can optionally be timed for a number of different durations in the game settings in the matchmaking lobby. The duration selected is the time limit per player, so the actual duration of the game can be at most twice as long.

Playing without a time limit is the alternative.

The timer of each player decreases from the time limit towards zero, and when the timer of one player reaches zero, that player loses the game, while the opponent wins the game, gaining 1 point.

In addition to these times, it is possible to select a time limit per move, which will usually speed up game play, while more advanced games will suffer from the lack of time to consider a move.