Chess

How to play

In short

• Tap one of your pieces, then a square with a dot. The dots show where the piece can go.
• Attack the opposing king so that it cannot escape and nothing can protect it. That is checkmate, and you win.
• White moves first, then the players take turns.

Goal

Each player has 16 pieces: a king, a queen, two rooks, two bishops, two knights and eight pawns. You win by checkmating your opponent: attacking their king so that no move can save it.

How the pieces move

• King moves one square in any direction. It may not move to a square the opponent attacks.
• Queen moves any distance in a straight line or diagonally.
• Rook moves any distance in a straight line: forward, backward or sideways.
• Bishop moves any distance diagonally and always stays on squares of one colour.
• Knight jumps in an L shape: two squares straight and one to the side. It is the only piece that jumps over others.
• Pawn moves one square forward, or two from its starting square. It captures one square diagonally forward.

Apart from the knight, no piece jumps. A piece captures by moving onto the square of an opposing piece, which leaves the board.

Special moves

• Castling: the king moves two squares towards a rook and the rook hops to the square next to it. It is allowed when neither the king nor that rook has moved, the squares between them are empty, the king is not in check and it does not pass through or land on an attacked square. On the board, tap the king and then the square two squares to the side, and the rook jumps over by itself. You can also drag the king.
• En passant: when an opposing pawn moves two squares and stops next to your pawn, you may capture it on your very next move as if it had moved only one square.
• Promotion: a pawn that reaches the last rank becomes a queen, rook, bishop or knight. The game asks which one.

Check, checkmate and stalemate

• Check: the king is attacked. The player must get out of check by moving the king, blocking with another piece or capturing the attacker. The game marks the king’s square in red.
• Checkmate: a check that cannot be escaped. The game ends and the player who gave checkmate wins.
• Stalemate: the player to move has no legal move and their king is not in check. The game is a draw.

Draws

Besides stalemate, the game is drawn in these cases, which the game detects on its own:

• the same position with the same player to move occurs three times,
• fifty moves by each player in a row without a capture or a pawn move,
• not enough material is left to checkmate: king against king, king and bishop or king and knight against king, or only bishops on squares of one colour.

Playing the computer

Before the game you choose the computer’s strength from 1 to 5 and your colour. Level 1 makes many mistakes and suits children and first games. Level 5 is a strong opponent that thinks the longest. The Hint button first shows a piece worth moving, and a second tap shows the square too. Undo takes back your last move and the computer’s reply.

Under Helpers you can switch on Show pieces in danger. A dashed red ring then marks any of your pieces that the opponent could win. It is off by default.

Playing friends by code

The Play with friends using a code button creates a room, and a friend joins with its code or QR code. Chance decides who plays White. Each player sees the board with their own pieces at the bottom. You can resign when it is your turn. If someone loses connection, the game waits 45 seconds and then the computer moves for them until they return.

Controls

Tap a piece and then the target square, or drag the piece there. Empty squares the piece can reach show a dot, and pieces you can capture show a ring (en passant: the pawn that will disappear). If a move is not allowed, the piece shakes and the game says why. The last move is highlighted in yellow.

With a keyboard, move around the board with the arrow keys, press Enter or Space to pick a piece and play the move, and Esc to cancel. The Flip button turns the board around. An unfinished game is saved in your browser and continues when you come back.

The pieces come from the Cburnett set (Colin M. L. Burnett) on Wikimedia Commons, BSD licence. Sources of graphics and licences are on the Licenses page.