Chess

• Objective
• Pieces
• Board
• Play
• End of Game
• External Links

At the beginning of the game one of the players has 16 light pieces and the second player has 16 dark pieces:

Light pieces	Dark pieces
- the King	- the King
- the Queen	- the Queen
- two rooks	- two rooks
- two bishops	- two bishops
- two knights	- two knights
- eight pawns	- eight pawns

The Chess is played on a square board of 8x8 cells.

The initial position of the pieces on the board is shown on the next picture:

Players move alternatively, starting from a player controlling white pieces.

No piece can be moved to a cell occupied by another piece of the same color.

If a piece moves to a cell occupied by an enemy piece the latter is considered to be captured and removed from the board. The capture is not mandatory, i.e. if one of the player's pieces can capture some enemy piece it's not required to do so.

If a piece A can capture an enemy piece B it's said that the A attacks B or that the B is under attack.

The King is said to be "in check" if it is under attack of some enemy piece (even if the attacking piece cannot move for some reason).

A player may never leave his king "in check" at the end of his move. The "in check" situation can be eliminated in one of the following ways:

• The king can be moved to a cell that is not under attack.
• The attacking enemy piece can be captured by one of the player's pieces (even by the king, if doing so does not put the king in check).
• The attack can be blocked by placing another player's piece between the king and attacking enemy piece (this is not possible if the attacking piece is a knight).

All possible moves for each type of the pieces are explained below.

The Bishop can move any number of empty cells in any diagonal direction. The bishop cannot jump over other pieces.

The Rook can move any number of empty cells horizontally or vertically. The rook cannot jump over other pieces. The rook is also moved during a castling.

The Queen can move any number of empty cells diagonally, horizontally, or vertically. The queen cannot jump over other pieces.

The Knight can move to the nearest cell that is not on the same row, column or diagonal. In other words the knight moves two cells horizontally or vertically and then one cell perpendicular to that. The Knight is the only piece that can jump over other pieces.

The Pawn can make several kind of moves and it captures enemy pieces in a different way comparing to other pieces:

• a pawn can move one cell forward on the same vertical column if that cell is empty;
• a pawn  can move two cell forward from its initial position if both cells are empty;
• a pawn  can capture an enemy piece on any of the two cells adjacent to the cell in front of the pawn (i.e., the two adjacent cells diagonally in front of the pawn);

• if an enemy pawn moves two cell forward from its initial position and lands on a cell horizontally adjacent to a player's pawn then the player's pawn can capture the enemy pawn "en passant" as if it moved forward only one cell rather than two, but only on the immediately subsequent move:

• If a pawn reaches the last row then it is promoted to a queen, rook, bishop, or knight of the same color. The player can choose any of the mentioned variants but, in practice, the pawn is almost always promoted to a queen.

The King can make two kinds of move:

• it can move to any adjacent onoccupied cell that is not under attack. It is considered that these cells are under attack even if the attacking piece cannot move for some reason;

• once per game the king can make a special move called "castling".  Castling includes moving the king two cells towards a rook and then placing the rook on the other side of the king, adjacent to it:

• The castling is only allowed if both a rook and the king meet the following conditions:

1. the king and the corresponding rook have never moved during the game;
2. no pieces are standing between the king and the rook;
3. the king may not currently be in check, nor may the king pass through or land on a cell that is under attack by one or more enemy pieces (though the rook is permitted to be under attack).
4. the rook must be the original one and not a pawn promoted to a rook.

If a player puts an enemy king in check and the opponent cannot eliminate it on his next move, then the game ends and the player wins. Such position is called a checkmate. On the following picture the black king  is in check (under attack of white rook) and there is no way for blacks to escape from this situation:

The game ends up in a draw if a player's king is not in check and he has no legal moves on his turn. I.e. the player has no other pieces (or all his pieces cannot move) and he cannot move his king without putting him in check. Such situation is called a stalemate. On the following picture the black king is not in check but he cannot move since each of the two unoccupied adjacent cells are under attack of the white rook:

The game ends up in a draw if there is no possibility for either player to checkmate the opponent. For example one player has a king and a knight and another only a king.

Any player can claim a draw if one of the following conditions exists:

• No pawn has been moved and no piece has been captured during fifty subsequent moves played by each player.
• The same board position has been repeated three times. The positions are considered to be identical if it is a turn of the same player and all pieces have the same rights to move, including the right to castle or capture en passant.

• Chess rules and history on Wikipedia.