rules.txt

Chess moves
King can move one square horizontally, vertically, or diagonally. At most once in every game, each king is allowed to make a special move, known as castling.
Queen can move any number of vacant squares diagonally, horizontally, or vertically.
Rook can move any number of vacant squares vertically or horizontally. It also is moved while castling.
Bishop can move any number of vacant squares in any diagonal direction.
Knight can move one square along any rank or file and then at an angle. 
The knight´s movement can also be viewed as an “L” or “7″ laid out at any horizontal or vertical angle.
Pawns can move forward one square, if that square is unoccupied. If it has not yet moved, the pawn has the option of moving two squares forward provided both squares in front of the pawn 
are unoccupied. A pawn cannot move backward. Pawns are the only pieces that capture differently from how they move. They can capture an enemy piece on either of the two spaces 
adjacent to the space in front of them (i.e., the two squares diagonally in front of them) but cannot move to these spaces if they are vacant. The pawn is also involved in the two special 
moves en passant and promotion.
Castling
Castling is the only time in the chess game when more than one piece moves during a turn. During the castling, the king moves two squares towards the rook he intends 
to castle with, and the rook moves to the square through which the king passed. Castling is only permissible if all of the following conditions hold:
-Neither king nor rook involved in castling may have moved from the original position;
-There must be no pieces between the king and the rook;
-The king may not currently be in check, nor may the king pass through or end up in a square that is under attack by an enemy piece 
(though the rook is permitted to be under attack and to pass over an attacked square)
En Passant
En Passant may only occur when a pawn is moved two squares on its initial movement. When this happens, the opposing player has the option to take the moved pawn “en passant” as if 
it had only moved one square.
Pawn promotion
If a pawn reaches the opponent´s edge of the table, it will be promoted – the pawn may be converted to a queen, rook, bishop or knight, as the player desires. 
The choice is not limited to previously captured pieces. Thus its´ theoretically possible having up to nine queens or up to ten rooks, bishops, or knights if 
all pawns are promoted.#