Play Dots and Boxes Online for Free
Dots and Boxes turns a plain grid of dots into a battle of patience and counting. Every turn you draw one line between two neighbouring dots, and the moment you close the fourth wall of a square you claim it and immediately go again — so a single move can cascade into a whole row of captured boxes. The twist is that nobody wants to draw the third side of a box, so the real game is about who runs out of safe moves first. Play it on a 3×3 up to a 6×6 grid against three AI levels or a friend on the same device.
How to Play Dots and Boxes
The board is a square lattice of dots, sized from 3×3 to 6×6 boxes (a 4×4 board is the default). A 4×4 board has 5×5 dots and 16 boxes to claim. Blue always moves first — and in solo play Blue is you, while the AI plays Red. On each turn you draw exactly one horizontal or vertical line joining two adjacent dots, and each line segment can only be drawn once.
When the line you draw completes the fourth side of a box, you claim that box in your colour and must take another turn straight away. Because one line can sit between two boxes, a single move can complete two boxes at once — and as long as you keep closing boxes, you keep moving. If your line completes no box, play passes to your opponent.
The game ends when every possible line on the grid has been drawn. Whoever owns the most boxes wins. Ties are possible only on grids with an even box count: a 4×4 (16 boxes) or 6×6 (36 boxes) can finish drawn, while a 3×3 (9) or 5×5 (25) always produces a winner because an odd number of boxes can't split evenly. An undo button lets you take back your last move while you learn — against the AI it rewinds your move and the computer's whole reply.
Chain Control: How to Win at Dots and Boxes
The opening is about avoiding the third side. A box with two sides drawn is a trap: adding the third side hands your opponent a free box. Early on, play only "safe" lines that leave every box with at most two sides. The grid eventually fills up and someone is forced to make the first sacrifice — your goal is to make that be your opponent, which often comes down to a parity count of how many safe moves remain.
The decisive idea is the chain. When boxes link into a connected run, whoever is forced to open the chain gives the whole run to the other player, who closes box after box on consecutive turns. So you don't want to win lots of small chains — you want to win the long ones. There's a well-known chain-parity rule of thumb: count the long chains and the number of dots on the board, and steer play so it's your opponent — not you — who has to open the biggest chain.
The expert move is the double-cross sacrifice. When you're handed a chain, the greedy instinct is to grab every box — but if you take all of them, you must then open the next chain yourself. Instead, take all but the last two boxes and decline them: draw the line that hands those two boxes back to your opponent. They score two, but they're then forced to open the next chain for you. Sacrificing two boxes to keep control of every remaining chain usually wins decisively. The same trick applies to closed loops, where you leave the last four boxes.
Against the AI here, the levels behave differently. Easy and Medium make outright random blunders sometimes (roughly a third of the time on Easy, about one in ten on Medium), so they will often hand you a chain for free — punish that and take it. Hard never blunders and penalises any move that gifts a three-sided box. On the 3×3, 4×4 and 5×5 boards Hard also searches noticeably deeper than Medium, so you'll need genuine chain counting; on the 6×6 board Hard and Medium search the same depth and Hard's only edge is that it stops blundering. Crucially, every level is greedy once a chain opens — it always runs the whole chain you give it — so the double-cross works beautifully: open nothing, force the AI to open a chain, then sacrifice two boxes to keep handing chains back and starve it of control.
Frequently Asked Questions
If I complete a box, do I really get another turn?
Yes. Closing the fourth side of any box claims it and gives you an immediate extra move. You keep going as long as each line you draw completes at least one box, which is how players run off long chains of captured boxes in a single turn.
Can one line claim two boxes at the same time?
Yes. A line that sits between two boxes can close both at once if each only needed that one side. This double-box move is the engine behind the "double-cross" tactic, where you deliberately hand two boxes to your opponent to force them to open the next chain.
Why is it bad to draw the third side of a box?
Drawing the third side leaves the box with only one open wall, so your opponent can complete it on their next move — and then take another turn. Giving away the third side is how you lose control, which is why strong play means making only safe two-side-max moves until you're forced to give one up. The Hard AI is built to avoid handing out these three-sided boxes.
Can a game of dots and boxes end in a draw?
Only on grids with an even number of boxes. A 4×4 board (16 boxes) or a 6×6 board (36 boxes) can finish tied 8–8 or 18–18, but odd-count grids like 3×3 (9 boxes) and 5×5 (25 boxes) always produce a winner since the boxes can't split evenly.
Should I always grab every box in a chain the AI gives me?
Not against the Hard AI. Taking every box forces you to open the next chain yourself. The expert play is the double-cross: take all but the last two boxes of a chain, then sacrifice those two so your opponent has to open the following chain for you. It works especially well here because the AI is greedy — it will always run a whole chain you open for it, so keeping control with small sacrifices steers the game your way.