Castling

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 permissible if all the following conditions hold:

• The king and rook involved in castling must not have previously moved
• There must be no pieces between the king and the rook
• The king may not currently be under attack, 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)
• The castling must be kingside (blue) or queenside (red).