Rules & objective
Trace every edge of the drawing exactly once.
- After choosing a start, each next dot must be connected to the current dot by an unused edge.
- Dots can be visited more than once. A line crossing without a numbered dot is not an extra junction you can select.
- Finish by using every edge. If you reach a dot with no unused exit too early, Undo lets you reconsider your route.
Key terms
- Edge
- A connection between two selectable dots.
- Degree
- The number of edges meeting at a dot.
- Odd-degree dot
- A dot with an odd number of connected edges.
Difficulty levels
| Level | What changes |
|---|---|
| Easy | Short paths with 3–5 edges. Three puzzles to explore. |
| Medium | Connected loops and branches with 6–8 edges. Three puzzles. |
| Hard | Denser drawings with 9–12 edges. Three puzzles; Undo stays available. |
Changing difficulty starts a fresh round. Personal bests are tracked separately.
This version on puzzle free online
Each difficulty contains three drawings. Easy uses 3–5 edges, Medium 6–8, and Hard 9–12. Next level cycles within the current tier; changing tiers returns to its first drawing.
Common questions
Must I hold the mouse down?
No. Select successive connected dots with taps or clicks.
Where should I start?
If the connected drawing has exactly two odd-degree dots, a complete trace must start at one and end at the other. If every dot has even degree, a complete trace can return to its start.
Explore this game in a new way
Keep exploring
Put the rules into practice.
Use the companion guide for a worked example, strategy and a small practice challenge.
Read the One Line guide ↗Browse all wiki articles