Dots & Boxes

Draw a line, close a box, go again. Simple to play and surprisingly deep to play well.

5×5 · most boxes · play a person instead

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Your move

Boxes:00

Opponent
Level

Master is part of Tessera Pro.

You play

Moves

No lines played yet.

How to play Dots & Boxes

  1. Players take turns drawing one line between two neighbouring dots.
  2. Draw the fourth side of a box and you claim it — and you must move again.
  3. That can chain: one line can close a box, then another, then another, all in the same turn.
  4. The game ends when every line is drawn. Most boxes wins.
  5. This board has twenty-five boxes, so a draw is impossible.

Published by the French mathematician Édouard Lucas in 1889 as la pipopipette, and played on the back of exercise books ever since. Its theory is not childish at all: Elwyn Berlekamp's work on chains and the double-cross showed that the whole game turns on who is forced to open the first long chain, and that giving boxes away on purpose is usually the winning move.

How to get better

Count the chains, not the boxes

The middlegame is about who runs out of safe lines first. Whoever is forced to open the first long chain usually loses it all.

Learn the double-cross

When you are handed a chain of three or more, take all but the last two, then draw the line that gives that pair away. You lose two boxes and keep the move — and the move is worth more than the boxes.

Never make a third side by accident

Any line that leaves a box on three sides is a free box for your opponent. Until the safe lines run out, treat those squares as off limits.

Parity decides it

The number of long chains on the board settles who has to open one first. Good players steer the middlegame to make that number odd or even, depending on which side of it they are on.

Why would I ever give boxes away?

Because taking every box means you have to move again when nothing is safe, and that hands your opponent the next chain — which is usually bigger. Leaving two boxes costs you two and buys you the move.

What counts as a chain?

A run of boxes joined so that opening one gives away all of them. Three or more is a long chain, and long chains are what the game is really about.

Can a game be drawn?

Not on this board. Twenty-five boxes cannot be split evenly, so somebody always has more.

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