Rules and notation

The handwritten chess board plays the ordinary rules of chess: castling, en passant, promotion, and draws by stalemate, repetition, the fifty-move rule and insufficient material. You give each move by writing it.

Write your move over the board in algebraic notation: e4, Nf3, exd5, O-O, e8Q. Write the characters one on top of the other (or beside each other) anywhere on the board; the reader works out where one character ends and the next begins. What it has read so far shows under the board.

The reader only knows the moves that are legal in the position, so a B cannot be read as an 8 or a b as a 6. A move is played as soon as what you wrote names exactly one legal move. The x, +, # and = are optional, 0 reads as O, and a pawn capture may be written as its destination alone.

When what you wrote fits several moves (Rd1 with two rooks that can reach d1, or e8 without the promotion piece) they are offered as chips and you tap the one you mean. When it fits one move that could also be the start of a longer one (O-O and O-O-O), the move waits as a chip until you tap it or write on. Move settles what is written now; Clear drops the ink.

• Squares are a file a-h (left to right from white's side) and a rank 1-8 (white's side first): e4.
• Pieces are K king, Q queen, R rook, B bishop, N knight; a pawn has no letter. Nf3 is a knight to f3, e4 a pawn to e4.
• Captures put an x before the square: Bxc6; a pawn capture starts with the pawn's file: exd5.
• Two pieces that can reach a square are told apart by their file or rank: Nbd2, R1e2.
• Castling is O-O on the king's side and O-O-O on the queen's.
• Promotion adds the new piece: e8Q (or e8=Q).
• Check and mate are marked + and #; here you can leave them out.

The bot plays four levels, from a look one move ahead with a wobble to four plies with captures beyond, and thinks on your device. You can choose your colour, undo (which takes back the bot's reply too), resign, and flip the board; your wins, losses and draws against it are kept in this browser. Two players here is a game for two on the same device: pass it across after each move. A friend online is a room for two: start one, share its eight-character code or link, and the server checks each written move and shows it to your opponent in your hand; offer a draw, resign, or play again with the colours swapped.

The position builder makes a board by writing: a piece letter in a square is that piece (K Q R B N white, k q r b n black, FEN's own letters). A second after your last stroke the piece fades in over the ink and is set; write again before then to change it, and if it read the wrong case, tap the runner-up chip.

A tap on an empty square is a pawn of the colour you used last, a quick second tap makes it the other colour; a tap on a piece flips its colour, and a quick second tap removes it. Castling rights follow the kings and rooks unless you untick them. The FEN is written beside the board (copy it, or paste one to load it), and "play from here" starts a game against the bot or for two players from that position.

Handwriting recognition by millirec, on your device: nothing you write is sent anywhere.