What are the rules of Number Link?
Number Link is a grid with pairs of equal numbers. Join each pair with a path that runs through neighbouring squares, side to side, never diagonally. Paths may not cross or share a square, and when you are done they fill the whole grid: no square is left empty. Each puzzle has exactly one way to do it.
Choose a grid size (6 × 6 is picked to begin with). Drag from a number to draw its path; drag back over it to shorten it, and drawing across another path cuts that path where you cross. A path ends when it reaches its other number. On a keyboard, press Enter on a number or a path to draw from there, use the arrows to draw, and Escape to stop.
| Grid | Pairs |
|---|---|
| 5 × 5 | 5 |
| 6 × 6 | 6 |
| 7 × 7 | 8 |
| 8 × 8 | 9 |
| 9 × 9 | 10 |
How do you solve Number Link?
- Start with the easy pairs. Numbers in a corner or along an edge have few ways out, and a pair that sits close together is usually joined by the short way.
- Run paths along the edges. The squares around the outside have to be filled by something, and often only one pair can reach them.
- Never wall off a gap. A path that cuts off empty squares no other pair can reach is wrong, and so is one that separates a number from its partner.
- Don't let a path double back beside itself. In a puzzle with one answer, a path never runs alongside itself: that bend could be cut short, leaving its squares to be filled more than one way.
How is your Number Link Puzzle time calculated?
Your result is the time from Start until every pair is joined and every square is used. Beside it are the times you used Check, which marks any square on the wrong path, and Hint, which draws one pair's whole path from the answer, cutting back any path in its way. There is no rating, because no published typical time exists for puzzles built like these.
Does every Number Link here have exactly one answer?
Yes. The 150 puzzles here were made ahead of time. Each starts with every square as a path of its own; paths whose ends sit side by side are joined at random until only a few long ones are left, and each path's two ends get its number. A puzzle was kept only if a search, extending the most hemmed-in path first, found exactly one way to fill the grid. The site's tests count every stored puzzle again.
Is this the same as Flow Free?
It follows the same rules. The puzzle is known as Numberlink, the name used by the Japanese publisher Nikoli, and phone games such as Flow Free use those rules with coloured dots instead of numbers. The puzzles here are this site's own. Here every path also has its own colour, and the numbers stay on so the puzzle never depends on telling colours apart. For a single path through every square, try Number Path; for a loop instead of paths, try Slitherlink.