How to play Dots and Boxes
The board is a grid of dots. Pick a 4 by 4 board (5 by 5 dots) or a 5 by 5 board (6 by 6 dots), and choose whether to play against the computer or against a friend on the same device.
Players take turns drawing a single line between two neighbouring dots, either across or down. Hover or tap near a gap to see a preview, then click or release to draw it. Lines you draw take your colour: blue for you or Player 1, orange for the computer or Player 2.
- When your line closes the fourth side of a box, the box is filled with your colour and you score a point.
- Completing a box gives you another turn straight away. One line can even complete two boxes at once.
- If your line does not complete a box, play passes to the other side.
The score for each side is shown above the board, and a coloured outline shows whose turn it is. The most recent line glows so you can see what just happened. When every line has been drawn, the player with the most boxes wins; a tie is possible on the 4 by 4 board. Against the computer, your total wins are saved on your device. The starting player alternates each time you press New game or Play again.
Controls
| Desktop | Move the mouse near the gap between two dots to preview a line, then click to draw it. Use the menus to change the board size or opponent. |
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| Mobile | Tap anywhere close to the gap between two dots to draw a line. You do not need to hit it exactly; the nearest free line is chosen. |
Tips and strategy
Do not draw the third side
The golden rule for beginners: avoid drawing the third side of any box, because that hands your opponent a free point and another turn. Early in the game there are plenty of safe lines, so use them up carefully.
Understand chains
Eventually every remaining line gives something away. By then the board is usually split into chains, rows of boxes joined together so that taking one opens the next. Whoever is forced to open a chain lets the other player collect all of it.
- When you must give something away, open the shortest chain you can.
- Count the long chains, those of three boxes or more, before the safe moves run out. Who ends up having to open them decides the game.
- Loops, chains that close back on themselves, give away even more when opened, so treat them with extra care.
The double-cross
Experienced players do not always take every box they are offered. When your opponent opens a long chain, take all but the last two boxes, then draw the line at the far end so those two are left as a pair for your opponent. They collect two boxes but must then move again, opening the next chain for you. Sacrificing two boxes to stay in control can win you many more.
Take free boxes, usually
If a box has three sides and there are no long chains left to worry about, grab it. Missing a free box is the most common way to lose points.
Playing the computer
- The computer always takes boxes it is offered and avoids giving away third sides while it can.
- It does not plan double-crosses, so learning chain control is the best way to beat it.
About Dots and Boxes
Dots and Boxes is a classic pencil-and-paper game for two players. It was described by the French mathematician Édouard Lucas in the late nineteenth century and has been played in classrooms and on the backs of notebooks ever since.
Although the rules take a minute to learn, the game has surprising depth. Mathematicians have studied it closely; it features in the book Winning Ways for your Mathematical Plays, and the ideas of chains and the double-cross are well known to strong players.
Our browser version is our own take on the game, built for PlayNook. It offers two board sizes, a computer opponent that follows simple sensible rules, and a two-player mode for sharing one screen. It runs entirely in your browser with no download or sign-up needed.
Frequently asked questions
Why did I get another turn?
Completing the fourth side of a box always earns an extra turn. Keep drawing lines until you make a move that does not finish a box.
Can the game end in a tie?
Yes, on the 4 by 4 board there are 16 boxes, so an 8 to 8 finish is possible. The 5 by 5 board has 25 boxes, so someone always wins.
How good is the computer?
It takes any box it can, avoids drawing third sides and, when forced, gives away as few boxes as possible. It does not plan advanced tricks like the double-cross, so good chain play can beat it.
Who moves first?
You or Player 1 start the first game, and the first move alternates each time you start a new one. Changing the board size or opponent resets it.
