The rules
- Start on cell 1.
- Draw one continuous line through neighboring cells (not diagonally).
- The line visits every cell of the grid exactly once.
- The line passes the numbers in order: 1, 2, 3 and so on, and ends on the highest number.
- You can’t cross a wall (a thick line between two cells).
Every puzzle has exactly one solution, and you reach it by logic, without guessing.
How to play here
- Drag: pull from the end of the line. Pull back along the line to erase. Clicking a cell already on the line cuts the line back to it.
- Keyboard: the arrows extend the line from its end. An arrow toward the previous cell, or Backspace, undoes the last step.
- Below the grid you can see how many cells are covered.
Difficulty levels
| Level | Size | What it takes |
|---|---|---|
| Easy | 5×5 | Tight cells and segments |
| Medium | 6×6 | + No loops, or reach once or twice |
| Hard | 7×7 | + Reach, 3 to 9 times |
| Expert | 8×8 | + Reach, 10 times or more |
Techniques
Tight cell
Every cell in the middle of the line connects to two neighbors. The start and the end connect to one. A corner, or a cell boxed in by walls, almost always dictates the path.
Segments
The line splits into segments: from 1 to 2, from 2 to 3, and so on. Each cell belongs to exactly one segment. Two cells that can’t be in the same segment can’t be next to each other on the line either.
No loops
The line never closes a loop. A connection that would close one is not allowed.
Reach
For each segment, check which cells it could reach without passing another number. A cell it can’t reach belongs to another segment. That’s how you spot when a segment has to sweep up a far corner.
Tips
- Never leave a cell stranded. If an empty cell has only one open neighbor left, it must be the end of the line.
- Check corners and walls before rushing to the next number.
- A long segment between two nearby numbers must take a detour. Think about which area it is meant to cover.