Checkers

How to play checkers

Checkers is a two-player game on an 8 by 8 board. Each player starts with 12 pieces on the dark squares of the three rows nearest them, and only the dark squares are ever used. Poozee plays by American rules, also known as English draughts: in Britain the same game is called draughts.

• Black moves first, then the players take turns.
• Men move one square diagonally forward onto an empty dark square.
• Jump to capture. If an opponent's piece is diagonally next to yours with an empty square behind it, you can jump over it and remove it. If you land where you can jump again, you keep going in the same turn.
• Jumping is compulsory. If you can jump, you must. When you have more than one jump, you pick which one, but once you start a multi-jump you have to finish it.
• Reach the far row to crown a king. A man that gets there becomes a king, and its turn ends. Kings move and jump one square diagonally, forward or backward.
• Win by capturing all of your opponent's pieces or leaving them with no legal move.

Playing on Poozee

• vs Computer: you swap sides every game, so half the time you play Black and move first. Your pieces are always at the bottom of the board. Easy makes plenty of mistakes, Medium plays solidly, and Hard looks many moves ahead.
• 2 Players: share one screen and take turns. The scoreboard keeps count for Black and Red.
• To move, tap or click a piece, then a highlighted square. For a multi-jump, tap each landing square in turn. When a jump is compulsory, the pieces that can jump are outlined.
• Hint (against the computer) lights up the move the Hard computer would play for you. Undo takes back your last move, along with the computer's reply.
• Draws: if 40 moves go by for each player with no capture and no man moving, the game is a draw.

Strategy basics

1. Keep your back row as long as you can. Your opponent can only crown a king by reaching it. Pieces left on your back row block that, so move them last. In our computer tests this was one of the two habits that mattered most.
2. Don't rush; move in groups. A man that runs ahead alone is easy to trap. A piece with a friend behind it can't be jumped from the front, because there is no empty square to land on.
3. Use forced jumps. Because jumping is compulsory, you can make your opponent's move for them. Giving up a piece on purpose can pull an enemy piece into a spot where you jump two back.
4. Trap a lone king in a single corner. With two kings against one, the lone king lasts about three times as long in a double corner or the center as it does in a single corner.

For the tests behind these tips, including two popular tips that didn't hold up, read how to win at checkers.

Worked example: giving one to get two

Squares are named like a chess board from Red's side: columns a to h from left to right and rows 1 to 8 from the bottom. Red has men on b2, c3 and b4. Black has men on b6, f6 and h6, and it is Red's move.

Red plays b4 to c5, right next to Black's man on b6. Black has to jump it (b6 over c5 to d4), because that is Black's only legal move. Now Red's man on c3 jumps twice: over d4 to e5, then over f6 to g7. Red gave up one man and took two. We checked this position with Poozee's game engine: Black has no other move, and the Medium and Hard computers both find the shot.

Pro tip: Before every move, look at what your opponent will be forced to do next. Compulsory jumps are the source of almost every trick in checkers.

Where the game comes from

The game is known as checkers in the United States and draughts in Britain. It was solved in 2007: a team led by Jonathan Schaeffer at the University of Alberta, using their program Chinook, showed that perfect play by both sides always ends in a draw. Their paper, "Checkers Is Solved", appeared in Science and puts the number of possible positions at roughly 500 billion billion. Computers had been working on the proof, almost without a break, since 1989.