Draw lines between dots to complete boxes. Claim more boxes than the AI to win. The classic pen-and-paper strategy game.
You go first · Complete a box for an extra turn
Click a gap between dots to draw a line
You claimed more boxes than the AI.
Press Enter to play again
Dots and Boxes is a classic pencil-and-paper strategy game invented by French mathematician Édouard Lucas in 1889. Two players take turns drawing one line segment between adjacent dots on a rectangular grid. When a player completes the fourth side of a 1×1 box, they claim it and earn a bonus turn. The player with the most claimed boxes at the end wins.
Dots and Boxes was analyzed mathematically by Elwyn Berlekamp, who proved that it has deep combinatorial complexity — comparable in depth to Go for large board sizes.
Each turn you draw one line between two horizontally or vertically adjacent dots. If that line completes a box, you claim it (marked with your initial) and get to draw another line immediately. The extra-turn rule creates chain reactions: skilled players engineer positions where one move opens a long sequence of boxes for their opponent to claim — or forces the opponent to open a chain for them.
Control the chains. Avoid completing the third side of any box — that gifts your opponent an easy score. Count chain lengths and try to control which chains get opened. The player who forces the opponent to start the first long chain usually wins. On Hard difficulty, master the "sacrifice": give up a short chain to maintain control of longer ones.
A chain is a sequence of boxes where completing one lets your opponent complete all of them. Advanced players count chains: with an even number of long chains, the second player tends to win; with an odd number, the first player tends to win. The "double-cross" tactic lets you stop a chain early, sacrificing two boxes but keeping the initiative for longer chains.
Not fully. Small boards (2×2, 3×3) have been solved by computer. Larger boards remain computationally intractable to solve exhaustively — there is no known perfect strategy for all positions on a 5×5 or larger grid. Elwyn Berlekamp's book The Dots and Boxes Game: Sophisticated Child's Play remains the definitive strategic reference.
Last updated: March 2026