Dots and boxes

Rules

Players take turns drawing one line between two neighbouring dots, across or down. A player who draws the fourth side of a box claims it and must draw another line. One line can complete two boxes at once. When every box is claimed, the player with more boxes wins. Choose 3 × 3, 4 × 4, 5 × 5 or 6 × 6 boxes in the table settings.

Chains and control

Early in the game nobody wants to draw the third side of a box, because it lets the opponent take it. Eventually every remaining line does so, and the board breaks up into chains: corridors of boxes where taking one box exposes the next.

Whoever is forced to open the first long chain usually loses, because the opponent takes almost all of it and keeps control. The way to keep control is to decline: take all but the last two boxes of a chain, then draw the line that hands those two boxes over. Your opponent takes them and must open the next chain for you.

Practical advice

• Do not take every box you can. Ask first whether taking it will force you to open a long chain afterwards.
• Count chains of three or more boxes as the board fills. Their number tells you who will have to open the first one.
• When you must give boxes away, give the shortest chain, and sacrifice early boxes to change who opens the long ones.
• Loops are closed chains. Declining a loop costs four boxes instead of two, so they work in favour of the side without control.

Mistakes the computer exploits

• Drawing a third side early for no reason.
• Taking the last two boxes of a chain out of habit and then opening the longest chain on the board.
• Ignoring small chains of one or two boxes, which are the tools for changing control.