The player controlling the white army is named “White” and the the player controlling the black pieces is named “Black”. White begins first and the players alternate moves after that. A move has to be made every turn, skipping isn’t allowed. Not even when having to move means losing. A game continues until a king is checkmated, a player resigns, or a draw is declared. Details are explained below. In addition, if the game is being played under a time constrain, players who exceed their time limit lose the game.
Each chess piece has its own method of movement. Moves are made to vacant squares except when capturing an opponent’s piece.
With the exception of any movement of the knight and the occasional castling maneuver, pieces cannot jump over each other. When a piece is captured, the attacking piece replaces the enemy piece on its square (en passant being the only exception). The captured piece is then removed from the game and may not be returned to play for the remainder of the game. The king can be put in check, but cannot be captured (see below).
The king can move exactly one square either horizontally, vertically, or diagonally. Only once per player, per game, is a king allowed to make a special move known as castling (see below).
The rook moves any number of vacant squares vertically or horizontally. It also is moved while castling.
The bishop moves any number of vacant squares in any diagonal direction.
The queen can move any number of vacant squares either diagonally, horizontally or vertically.
The knight moves to the nearest square not on the same rank, file, or diagonal. In other words, the knight moves two squares horizontally then one square vertically, or one square horizontally then two squares vertically. Its move is not blocked by other pieces, it basically jumps to the new location.
Pawns have the most complex rules of movement:
- If the square infront of a pawn is unocccupied, the pawn can move forward one square. If it has not yet moved, each pawn has the option of moving two squares forward, given both squares in front of the pawn are unoccupied. A pawn cannot move backwards.
- 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 consists of moving the king two squares towards a rook, then placing the rook on the other side of the king, adjacent to it. Castling is only allowed if all of the following conditions are met:
- The king and rook involved in castling have not previously moved
- There are no pieces between the king and the rook
- The king currently isn’t in check, and isn’t going to be passing through or ending up in a square that is under attack by an enemy piece (though the rook is permitted to be under attack and can pass over an attacked square)
If player A’s pawn moves forward two squares and player B has a pawn on its fifth rank on an adjacent file, B’s pawn can capture A’s pawn as if A’s pawn had only moved one square. This capture can only be made on the immediately subsequent move. For example: if the white pawn moves from a2 to a4, the black pawn on b4 can capture it en passant, ending up on a3.
If a pawn advances to its eighth rank, it is then promoted to a queen, rook, bishop, or knight of the same color. The choice here is at the discretion of the controlling player. The choice is not limited to previously captured pieces. Hence it is theoretically possible for a player to have up to nine queens or up to ten rooks, bishops, or knights if all of their pawns are promoted.
This is a companion discussion topic for the original entry at https://constructarca.de/game/chess/