How to win at Dots and Boxes: strategy for beginners

Dots and Boxes looks like a game of luck: you draw lines, somebody gets stuck drawing a third side, and the other player cleans up. Strong players win almost every game, though, because the endgame follows simple patterns once you can see them. This tutorial walks you through your first game, then explains the ideas that win: safe lines, chains and loops, the double-cross and the long chain rule. You can try each one straight away in Dots and Boxes against the computer.

What you will learn

• How a game flows from the safe opening to the endgame
• Why the third side of a box is the most important line in the game
• What chains and loops are, and which one to give away first
• The double-cross, the all-but-two trick that keeps control
• The long chain rule, explained with simple counting

If you need the rules first, read how to play Dots and Boxes.

Your first game, step by step

1. Open the game, choose vs Computer, pick Easy and set the board to 3×3. Start.
2. Draw lines anywhere for the first few turns. On an empty board no line can give a box away.
3. Before every line, look at the two boxes beside it. If either already has two sides, your line would be its third side. Pick another line.
4. Watch the computer. When it draws a third side, take the box by drawing the fourth, then draw again.
5. Sooner or later every line left gives something away. Find the line that gives away the fewest boxes and draw it.
6. Count the boxes at the end. Then press Rematch, move up to Medium, and try the same plan.

Easy closes every box you offer it, but otherwise draws at random, so it hands you boxes. Medium never draws a third side while it has a choice, which means the game really is decided in the endgame. That is where the rest of this guide comes in.

Strategy tips that win games

1. Never draw the third side (while you have a choice)

A box with three sides is a present for the next player. Early in the game most lines are safe: they give no box its third side. Draw safe lines and wait. The player who runs out of safe lines first has to start giving boxes away.

2. Take what is offered, usually

When your opponent draws a third side, close the box. You score and draw again, and the extra line may let you take the next box too. Taking free boxes is right almost all the time; the exception comes in tip 5.

3. Chains and loops

As safe lines run out, the open boxes link up. A chain is a row of boxes where each has two sides drawn: draw any line into it and the next player can take the whole chain, one box after another. A loop is a chain that closes back on itself.

Chains of one or two boxes are short. Chains of three or more are long, and long chains decide the game.

4. Give away the smallest piece first

When every line left gives something away, look at all the chains and loops and open the smallest. Giving away one box is better than giving away five, and each piece you hand over makes your opponent move next.

When you give away a chain of two, draw the middle line between the two boxes, not a line at one end. From the end, your opponent could refuse both boxes and hand them back to you at the right moment (see the next tip). From the middle, each box gets its third side on its own, and your opponent can only take them.

5. The double-cross: take all but two

Here is the trick that separates beginners from strong players. Your opponent opens a long chain for you. Instead of taking every box, take all of them except the last two. Then, instead of closing those two, draw the line at the far end of the chain.

Your opponent now takes the two boxes with one line (that line is the “double-cross”) and then has to draw again. If every line left is part of another chain, they have to open it for you. You gave up two boxes to win the next chain, and you can repeat the trick on every long chain until the last one, which you take completely. Holding on to that position is called keeping control. With a loop, the same trick costs four boxes: take all but four and draw the line that splits them into two pairs.

6. When to keep control, and when to just take everything

Keeping control costs two boxes per chain (four per loop), so it only pays when the chains still to come are worth more. A simple test before you finish a chain:

• If what is left is one more long chain, keep control: you give away 2 and win the whole last chain.
• If what is left is only a box or two, take everything. Handing back two boxes to win one is a bad trade.
• If it is the last chain on the board, take it all, of course.

The computer on Hard does this count for every chain and loop, so play it once you know the trick. It will happily take a short chain from you and keep control of the long ones.

7. The long chain rule, simply explained

Control at the end usually goes to whoever gets the parity, odd or even, right before the safe lines run out. Strong players steer it with a counting rule:

If you moved first, you want the number of dots plus the number of long chains to be even. If you moved second, you want it to be odd.

Loops don’t count, only chains of three or more. On the boards here:

So on the default 4×4 board, the player who started wants one or three long chains, and the other player wants two (or none). In the middle of the game, use your safe lines to shape the board: join two short pieces into one long chain, or cut a long chain in two with a line across it, until the count suits you. You don’t need to get it perfect. Just knowing which count you want turns random lines into a plan.

Common beginner mistakes

• Drawing a third side to “get it over with”. Count first: there may still be a safe line somewhere.
• Opening a long chain while a short one is still available. Give away the small pieces first.
• Giving away a chain of two from the end. Use the middle line, so it can’t be handed back.
• Always taking every box. In the endgame, the last two boxes of a chain are often worth more as a gift.
• Forgetting the extra line. After you close a box you must draw again, so plan where that line goes before you take the box.

A practice plan

1. Easy, 3×3: learn to spot third sides and to take every box that is offered.
2. Medium, 4×4: the opening becomes a fight over safe lines. Practise giving away the smallest piece when you run out.
3. Hard, 4×4: try the double-cross every time you receive a long chain, and see how often you can keep control.
4. Hard, 5×5 or 6×6: longer chains, more counting. Use the long chain rule to plan your safe lines.

Use Undo freely while you practise: take back a line, try the other choice, and see how the endgame changes. When you are ready, challenge a friend on one device in Dots and Boxes, and if you enjoy grid games, try the five-in-a-row race of Gomoku next.