How to play dots and boxes
The board is a grid of dots. Players take turns drawing one horizontal or vertical line between two neighboring dots. If your line completes the fourth side of a box, that box is yours (it fills with your color) and you must draw another line. A single line can close two boxes at once. When every line has been drawn, the player with more boxes wins. Blue moves first.
Tap or click between two dots to draw a line; dashed lines show the moves still available. Choose a 3×3, 4×4 or 5×5 box board with the Board option. You can play the computer or a friend on the same screen, and Undo takes back your move and the computer's reply.
Computer levels
Easy often takes boxes but plays many careless lines. Medium always takes free boxes and avoids drawing the third side of a box while safe moves remain; when it must give something away, it gives the fewest boxes possible. Hard does the same in the opening, and once no safe moves remain on a small enough board it calculates the rest of the game exactly – including the famous "double-cross" sacrifice – to win the endgame. Results are stored per level on your device.
Strategy tips
- Never draw the third side of a box unless you have to – it gives your opponent a free box.
- Count the chains. In the endgame the board breaks into chains of boxes. Whoever is forced to open the first long chain usually loses.
- Give away short chains first. When every move gives something away, open the smallest chain.
- Learn the double-cross. When taking a long chain, sometimes it is better to take all but the last two boxes and leave them with one line. Your opponent takes 2 but must then open the next chain for you.
- Don't be greedy too early. Sacrificing one or two boxes to keep control of the long chains often wins the game.
About the game
Dots and boxes was described by the French mathematician Édouard Lucas in the 1880s and has been a favorite pencil-and-paper game in schools ever since. It looks simple, yet it has deep mathematics behind it, studied in books on combinatorial game theory. This version is free, needs no paper, and keeps working offline after the first visit.
FAQ
What happens when I complete a box?
You score that box and must draw another line. Closing two boxes with one line scores both.
Who moves first?
Blue moves first. Use Who starts to let the computer play Blue.
Which board size should I choose?
3×3 games take a minute and are good for learning. 4×4 is the classic size, and 5×5 gives longer games with more chains.
What is the double-cross trick?
It means declining the last two boxes of a chain with a single line, so your opponent must take them and then open the next chain for you.
Can I play with a friend offline?
Yes. Choose 2 Players and share the screen. The page works without internet after the first visit.