Käsekästchen

Draw a grid of dots (commonly 6x6 or larger). Players choose who goes first. Each player needs a different color pen or uses initials to mark claimed boxes.

The player who has claimed more boxes when all are completed wins. Count the boxes marked with each player's initial.

Players take turns drawing one horizontal or vertical line between two adjacent dots. If a line completes the fourth side of a 1x1 square, that player claims the box (marking it with their initial). Completing a box earns an extra turn - continue playing until you don't complete a box.

In the opening, avoid completing three sides of any box (setting up your opponent). Create 'chains' of three-sided boxes to capture in sequence. When forced to open a chain, give away the shortest chain possible.

Dots and Boxes was first published in the 19th century by French mathematician Edouard Lucas. Despite simple rules, optimal play requires complex combinatorial analysis.