How to play Chess
Chess is played on an 8×8 board by two players, White and Black. These are the rules used on Turnpan.
The board and setup
The board is placed so each player has a light square in the right-hand corner. Each side starts with a king, a queen, two rooks, two bishops, two knights and eight pawns. White moves first, and then the players take turns, one move each.
How the pieces move
The king moves one square in any direction. The queen moves any number of squares in a straight line or diagonally. The rook moves in straight lines, the bishop diagonally. The knight jumps in an L shape (two squares one way, one square to the side) and is the only piece that can jump over others. A pawn moves one square forward, or two from its starting square, and captures one square diagonally forward.
Capturing
You capture an enemy piece by moving onto its square; it leaves the board. Capturing is never compulsory. No piece can move through another, except the knight.
Check and checkmate
A king under attack is in check, and the player must get out of check at once: move the king, block the attack, or capture the attacker. You may never make a move that leaves your own king in check. If there is no way out, it is checkmate and the game is over.
Castling
Once per game the king can castle: it moves two squares towards a rook, and that rook jumps to the square the king passed over. Neither piece may have moved before, the squares between them must be empty, and the king may not be in check, pass through an attacked square, or land in check. On Turnpan you castle by moving the king two squares, or by moving it onto its own rook.
Try it: tap or drag the marked piece to its square.
En passant
When a pawn moves two squares from its starting square and lands beside an enemy pawn, that enemy pawn may capture it as if it had moved only one square. This is allowed on the very next move only.
Try it: tap or drag the marked piece to its square.
Promotion
A pawn that reaches the far rank must become a queen, rook, bishop or knight of the same color — almost always a queen. On Turnpan a picker opens on that square so you can choose.
Try it: tap or drag the marked piece to its square.
Winning
You win by checkmating your opponent's king, when your opponent resigns, or when your opponent runs out of time on a clock and you still have enough material to mate.
Draws
The game is drawn by stalemate (the player to move has no legal move but is not in check), when neither side has enough material to checkmate, when the same position occurs three times, after 50 moves each with no capture or pawn move, or when both players agree. Turnpan applies these draws automatically, so there is nothing to claim.
The clock
Timed games use a chess clock: in 3 + 2 each player has three minutes and gains two seconds after every move; in 10 + 0 each has ten minutes and no increment. The clock turns red under 30 seconds and pulses under 10.
Move notation
Moves are written in algebraic notation: the files are a to h, the ranks 1 to 8, and each move names the piece (K, Q, R, B, N; nothing for a pawn) and its destination, such as Nf3 or e4. A capture adds x (Bxe5), castling is O-O or O-O-O, a promotion adds =Q, and + marks check, # checkmate.