How to play Untangle
Untangle is a planarity puzzle: a web of dots joined by straight lines, drawn as a mess. Drag the dots around until no two lines cross.
Every puzzle is built from a drawing that has no crossings, so a solution always exists. The clock starts on your first drag.
Rules
- Lines that still cross another line are drawn in red dashes; the counter above the board shows how many crossings are left.
- Lines only meet at the dots they connect. Touching a line with a dot that is not one of its ends also counts as a crossing.
- The puzzle is solved the moment the last crossing is gone. Your time and the number of drags are saved.
- Easy has 10 dots, Medium 21 and Hard 36. A puzzle in progress is kept if you leave the page.
Controls
- Drag
- Move a dot (mouse or finger)
- 1 / 2 / 3
- Easy, Medium or Hard
- N
- New puzzle
Tips
- Find a dot with only two lines and tuck it between its neighbours first: small triangles fall into place quickly.
- Spread the dots out over the whole board before fine-tuning; crowded clusters hide crossings.
- Hover a dot to see its lines darken — it shows you exactly what you are about to drag along.
- Work from the outside in: build a clean outer ring, then place the inner dots one at a time.
About Untangle
Planarity was created by John Tantalo in 2005 as a Flash game, using a puzzle generator by Mary Radcliffe: random straight lines whose crossing points become the dots. It spread quickly and has been cloned countless times since as “untangle” games on phones and in browsers.
This version uses the same line-based generator, so every puzzle is guaranteed to have a solution, with three sizes, a solve timer and your best times kept in your browser.
Questions
Is every puzzle solvable?
Yes. Each puzzle is generated from a set of straight lines whose crossing points become the dots, so a drawing with no crossings always exists. You only have to find it.
How is the time measured?
The clock starts when you first drag a dot and stops when the last crossing disappears. It pauses while the tab is hidden, and a puzzle in progress is saved with its time.
How do I play Untangle on a phone?
Drag the dots with your finger. You can grab a dot by touching close to it, so even the 36-dot Hard puzzle works on a small screen.
What does a red line mean?
A red dashed line crosses at least one other line. When there are no red lines left, the puzzle is solved.