Knight's tour

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A knight moves two squares one way and one square the other. Move it so that it lands on every square of the board exactly once. That path is called a tour.

Every square the knight can move to carries a mark. Tap one to move there. A square it has already used, or a square it cannot reach in one move, is refused: the knight does not move, the square it refused is marked for a moment, and the line under the board says why.

A square the knight has used keeps the step number it was, and a thin brass line joins the squares in order. So the whole path so far is on the board.

Easy is a five by five board and the knight starts in a corner. Standard is six by six and the page picks the square it starts on. Challenge is eight by eight and you pick the square. Every square offered is one a full tour really starts from.

It is easy to leave a square with no way in. When there is no move left, the board says so and Undo takes the knight back one square at a time. Start again puts it back where it began.

Hint plays one move out to the end of a full tour before it offers it, so a hinted move never strands the board. It counts as one hint. If no move can finish the board, it says that instead, and that counts as one hint too. On a large board it sometimes runs out of room to work the answer out at all. It says so, and that answer costs you nothing. A board finished with a hint is saved to your statistics and counts as finished there. It is left out of your solving time and out of the shared community numbers.

Show onward moves puts a number on every square the knight can move to. The number is how many moves it would have from that square. Warnsdorff's rule of 1823 is to take the smallest one, because a square with few ways in is the one to use before it has none. Turning the numbers on counts as one hint, once for the round.

If the last square is a knight's move from the first, the tour is closed and the knight could go round again. An open tour ends anywhere else. A five by five board has an odd number of squares, so a tour on it is always open.

The result is the squares used, the moves you took back, the hints you used and the time. The clock starts on your first move and stops when the last square is used.

The score says how you did on this board. It is not a speed record, and it says nothing about any other puzzle. A board you leave before it is finished is not saved.

The statistics page compares boards of the same size. Every saved board is a finished tour, so what it shows is your solving time and how many moves you took back. Boards finished with a hint are left out of the time.

Visit the squares near the edge early, and take the square with the fewest ways on. Learn why the edges go first