How to play Slitherlink

What you need

• A pencil and an eraser
• The printed puzzle sheet, or dotted paper
• One player, or two racing on copies

How to set up

The loop runs along the gaps between neighbouring dots. A number in a box says how many of that box's four sides the loop uses; boxes without a number can have any count.

1. 1. The puzzle is a square of dots: here six by six, making twenty-five boxes.

2. 2. Some boxes hold a number from 0 to 3.

3. 3. Draw short lines between neighbouring dots, and cross out gaps the loop cannot use.

4. 4. Finish with one closed loop that agrees with every number.

How to play

• Draw a line where the loop must go and a small cross where it cannot.
• Each dot has no line or exactly two: the loop never branches or crosses itself.
• Start with zeros, threes and corners, then follow what they force.

How to win

Draw a single closed loop through the dots. Solved when the lines form one loop and every number is matched.

Tip A 3 next to a 0 is a gift: the 3 must use the three sides away from the 0.

Variants

5 × 5

Twenty-five boxes: a gentle loop.

7 × 7

Forty-nine boxes and fewer numbers to lean on.