Puzzles

A puzzle is a position from which one side can force a clear goal: close a mill, win the game, take a corner or most of the remaining boxes. You play the moves; the computer answers with the most stubborn defence it can find. A move that throws the result away is taken back so you can try again.

How difficulty works

In every game, puzzles #1 to #14 count as easy, #15 to #27 as medium and #28 to #40 as hard. Easy ones are two-move ideas; medium ones ask for three moves or an exact eight-square reversi ending; hard ones go deeper still.

• Reversi puzzles

  40 puzzles

  Reversi puzzles come in two kinds. The easy ones ask you to force your way into a corner within two moves. The medium and hard ones are exact endings with eight or eleven empty squares in which only one move wins; every other move was checked to draw or lose.

  Easy 1–14Medium 15–27Hard 28–40
• Four in a Row puzzles

  40 puzzles

  In every Four in a Row puzzle the side to move wins by force in exactly two, three or four moves, and only one first column does it. The solution was checked against every reply, and the hard ones agree with an exact solver.

  Easy 1–14Medium 15–27Hard 28–40
• Mill puzzles

  40 puzzles

  Mill puzzles start from positions taken out of real games. The easy and medium ones ask you to close a mill in exactly two or three moves against every defence, in the placement or the sliding phase; the hard ones ask for the whole game.

  Easy 1–14Medium 15–27Hard 28–40
• Dots and Boxes puzzles

  40 puzzles

  Dots and Boxes puzzles are endgame positions on 3×3, 4×4 and 5×5 boards. The task is to take at least a given number of the remaining boxes against the best defence. In every one, exactly one line is best, and the obvious move of taking boxes or giving the fewest away falls short.

  Easy 1–14Medium 15–27Hard 28–40
• Draughts puzzles

  40 puzzles

  Each draughts puzzle is a short forced win with English rules: in two, three, or four to five moves every defence loses all its pieces or its last move. Expect sacrifices that use the compulsory capture and kings chasing the final men.

  Easy 1–14Medium 15–27Hard 28–40
• Five in a Row puzzles

  40 puzzles

  Five in a Row puzzles are forcing wins in two, three or four moves. Every move of the solution makes a four, so the defence is forced, and the engine checked that nothing faster wins and that the key move is the only quick start.

  Easy 1–14Medium 15–27Hard 28–40