Chess rules

Overview

Chess is a game played by two persons (or computers). One is called white ane one is called black (the color of the board need not be black and white but the name of the players stay). Chess is turn-based and white always start (that is white makes a move, black makes a move, white makes a move...). One move consist of one white move and one black move.

Goal of the game

The goal of chess is to checkmate (capture) the opponent's king. The king is checkmated when it cannot avoid capture by one of the opponent's pieces.

Check

When the king is threatend, but can move to avoid capture, then we have a check. A king may never be left in check and so a move out of the (bad) situation is needed immediatly. A king may never move himself into check, since that would lead to the capture in the next move. There are three things too choose from when in check.

The attacking piece may be captured
A piece may be moved in between the king and the attacking piece in order to block the attack
The king may simply move out of check itself

Pieces

Here is a brief description of how each of the pieces move.
Pieces are only removed from the board when they are captured. Pieces move on the board and are blocked by other pieces (no matter the color). The exception is the knight who jumps from one position to another and therefor is not blocked by other pieces. Pieces may only move to blank squares and squares occupied by a piece belonging to the opponent.

King

This is the most important piece because if it is captured the game is over.

The king may move one step in each direction.

Castling

This is a very special move. may only be done under certain conditions:

If the king and the rock involved are unmoved
The squares between them are empty
The king is not under check before the move
The king is not in check after the move
The king doesnt move on a threatend square (that is the rock may not be threatend after the move

In a king-side (or short) castling the king moves from e1(e8 for black) to g1(g8) and the rock move from h1(h8) to f1(f8).
In a queen-side (or long) castling the king moves from e1(e8 for black) to c1(c8) and the rock move from a1(a8) to d1(d8).

Queen

This is the most poverfull piece on the board The queen may move in any direction (straight lines only) any number of steps.

Rock

This is a poverfull piece May move as many sqares as desired, horizontally or vertically.

Knight

Move in an L-shaped manner first one square horizontal then two squares vertical or one square vertical and two squares horizontal.
Since this piece jumps over other pieces it can be quite poverfull.

Bishop

Since this piece cant reach all squares on the board it is weaker than the rock
May move as many sqares as desired, diagonally only.

Pawn

This is the weakest piece in the game, but there is eight of them (on each side) and used correctly they may be very powerful. If a pawn reaches the other edge it is promoted to one of the other pieces (Rock, Knight, Bishop or mostly Queen).

A pawn may only move one step forward for each move it makes. The pawn may only capture pieces that stands diagonaly forward (in his move-direction that is). An unmoved pawn may start moving by going two steps forward (if thoose positions are empty).

En-passant

Is a special move a pawn may use: if a pawn(PW) is taking two steps out and there is another pawn(PB) that could have taken it if had only moved one step then PB can move in behind PW and capture it as if it only had moved one step forward.