How to Win at Dots and Boxes: Chains and the Double-Cross
To win at Dots and Boxes, play safe lines (never a box's third side) for as long as you can, then take control of the long chains. When your opponent opens a chain, take all of it except the last two boxes and hand those two back with one line (the double-cross): they get 2 boxes but must open the next chain for you. Plan ahead with the long chain rule so the chains fall your way.
1. Safe lines and the endgame
Every game has two parts. First, both players draw safe lines that give no box a third side. Sooner or later safe lines run out, and every move hands boxes to the other player. Whoever is forced to move first in that endgame usually loses, so the real game is about who runs out of safe lines first.
2. Chains
A chain is a row of boxes joined so that taking one box gives you the line for the next. Once any line inside a chain is drawn, the other player can take the whole chain, one box after another.
- Short chains (1 or 2 boxes) are cheap to give away.
- Long chains (3 boxes or more) decide the game.
- Loops (a chain that closes on itself) are worth even more to the player who gets them.
3. The double-cross: give two to win many
This is the trick that separates good players from beginners. When your opponent opens a long chain, don't take every box. Take all but the last two, then draw the line at the far end of the chain. The last two boxes are left with one line between them.
Your opponent takes the two boxes with a single line, but then has to draw again, and the only lines left open another chain for you. Give 2, take the rest: over two or three chains, this wins most games.
When you have to give a chain of two away yourself, draw the line in the middle, not at an end. Then your opponent can't double-cross you back.
4. The long chain rule
For two players there's a simple counting rule, worked out by the mathematician Elwyn Berlekamp. On a grid with an even number of dots (like 4 × 4 or 6 × 6), the first player wants an even number of long chains, the second player an odd number. On a grid with an odd number of dots, it's the other way round.
While safe lines last, steer the board: split a long chain in two, or join two short ones into a long one, to make the count come out your way.
5. Quick checklist
- Never draw a third side while safe lines exist.
- Count the long chains and work toward your number.
- When forced to give boxes, give the smallest chain first.
- Give a 2-box chain with its middle line.
- When you get a long chain, double-cross at the end to keep control.
Practise on the GameLake Dots and Boxes game: Hard Hops uses chains and the double-cross, and Teach me shows a good line with the reason. New to the game? Start with how to play Dots and Boxes.
Frequently asked questions
What is the trick to winning Dots and Boxes?
The double-cross: when your opponent opens a long chain, take all but the last two boxes and hand those two back. They have to open the next chain for you.
Is it better to go first or second in Dots and Boxes?
Neither is clearly better. What matters is the long chain rule: on grids with an even number of dots, the first player wants an even number of long chains.
What is a chain in Dots and Boxes?
A row of boxes where each one you take gives you the line for the next. Once a chain is opened, one player can take all of it.
What is the long chain rule?
On a board with an even number of dots, the first player should aim for an even number of chains of 3 or more boxes, the second player an odd number. On an odd-dot board it flips.
How do you avoid giving away boxes?
Never draw the third side of a box while there's still a safe line elsewhere. When none are left, give away the shortest chain.