Dots and boxes strategy
Dots and boxes strategy: chains, giving away two boxes and the long chain rule
Dots and boxes is won at the end, by the player who takes the long chains. Early on, never draw the third side of a box. Once only chains are left, leave the last two boxes of a chain to your rival so they must open the next one, and steer the number of long chains with the long chain rule.
Early game: no third sides
A box with three sides drawn is a free box for the next player. In the first part of the game, both players draw lines that do not complete a third side, until no such lines are left. Then someone has to give boxes away.
See the chains
By then the board has split into chains, rows of boxes where taking one box opens the next, and loops, chains that close on themselves. A chain of three or more boxes is a long chain. Short chains of one or two boxes are cheap to give away; long chains are what the game is about.
Leave two boxes: double-dealing and the double-cross
When your rival opens a long chain, take every box except the last two. Then draw the line at the far end that leaves those two as a pair. Berlekamp calls this sacrifice a double-dealing move. Your rival takes both boxes with one line, a double-cross, but their turn then forces them to open the next chain, which you take.
Giving away two boxes to win the next chain is the move that separates good players from beginners. Counting double-crosses is also how the long chain rule below is derived.
The long chain rule
On a rectangular grid of dots, count the dots and the long chains you expect at the end.
- The first player wants dots plus long chains to be even.
- The second player wants it odd.
- On a 5 by 5 grid of dots (25 dots), the first player wants an odd number of long chains; the second player wants an even number.
- Split or join chains in the middle game to steer the count your way.
Sources
- Elwyn Berlekamp, The Dots and Boxes Game: Sophisticated Child's Play (A K Peters, 2000), on chains, double-dealing, the double-cross and the long chain rule
Back to the dots and boxes rules
More strategy
Strategy questions
What is the long chain rule in dots and boxes?
On a rectangular grid of dots, the first player wants the number of dots plus the number of long chains to be even, and the second player wants it odd.
Should you always take every box you can?
No. At the end of a long chain, leaving the last two boxes to your rival often wins you the next, bigger chain. That sacrifice is called a double-dealing move; your rival's line that takes both boxes is a double-cross.
Updated November 4, 2026 by the team.