Number Link

How to play Number Link

Number Link is a classic Japanese logic puzzle, also known as Arukone. The grid shows pairs of dots. Both dots of a pair have the same colour and the same number. Your job is to join every pair with a line.

Goal

Connect all pairs so that the lines fill every square of the grid. Lines may not cross, branch or share a square. Each puzzle has exactly one solution.

Turn by turn

1. Press on a dot and drag. A line in that colour follows your finger or mouse from square to square, up, down, left or right.
2. Reach the other dot of the same colour to complete the pair. The dots light up when they are linked.
3. Drag back over your own line to shorten it. Press on the middle of a line to keep only the part up to that square and carry on from there.
4. If you draw through another colour's line, that line is cut at that square. You cannot pass through a dot of another colour.
5. Press Undo to take back the last line you drew. Stuck? Hint draws one correct line for you.

Keyboard

Move between squares with the arrow keys. Press Enter or Space on a dot or line to pick it up, then draw with the arrows. Press Enter, Space or Escape to put it down.

Levels

There are 60 levels. They start on a small 5×5 grid and grow to 9×9 with up to twelve pairs. Every puzzle is built by the game and checked by a solver to make sure it has one solution only. Solved levels get a check mark, and your best move count is saved.

End of the level

The level is solved when all pairs are linked and no square is left empty. If all pairs are linked but some squares are empty, look for a line that can take a detour. Enjoyed it? Try Sudoku for another logic challenge.

Strategy tips

• Start at the edges. Dots near the border and in corners have few ways to go. Lines along the edge are often forced.
• Link close pairs first. Two dots that sit next to each other or very near often take the short way, but check that no square gets cut off.
• Look for dead ends. An empty square with only one free neighbour must be the end of a line, which is impossible. Change the lines around it.
• Lines hug each other. In a unique puzzle, long lines usually run side by side along walls and other lines, not through the open middle.
• Count the space. If a region is cut off, it must contain both dots of some pair, or it can never be filled.