Untangle Puzzle

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Untangle Puzzle is a free online untangle game — the classic planarity puzzle — playable straight in your browser with no download and no account. You are given a web of dots joined by lines, thrown onto a circle so that almost everything crosses. Drag the dots one at a time until not a single line crosses another. Every line still involved in a crossing is drawn in red, so you are never hunting by eye across forty edges; when the last red line turns white the puzzle solves itself, with no submit button. What makes this version fair is how the puzzles are made. Each one is grown by repeated triangle subdivision — a new dot is dropped strictly inside an existing triangle and joined to its three corners, which is a move that cannot create a crossing — so the layout the puzzle was generated from is itself a perfect, crossing-free solution. The test suite checks exactly that for all ten levels across several seeds, which means no puzzle here can be impossible. You do not have to find that particular arrangement, though: any layout with zero crossings wins, and there are always many. Ten levels run from a six-dot first knot to a twenty-three-dot Gordian, edges are thinned after generation so no board becomes an unreadable mesh, and every dot is guaranteed at least two connections so nothing dangles. Hint snaps the most tangled dot into a position that works, New Puzzle reseeds the same level to a different board, and nothing anywhere is timed.

How to play Untangle Puzzle

1. The board starts with every dot spread around a circle, which is the most tangled arrangement there is — the mess is the puzzle, not a mistake.
2. Drag any dot to move it. Lines follow the dots they connect, so moving one dot changes every line attached to it.
3. Any line that still crosses another line is drawn in red. White lines are already clear. That colouring is the whole navigation system for the puzzle.
4. The counter in the header is the number of crossings left, and it updates live while you drag — so you can see a move working before you let go.
5. The puzzle finishes the moment the count reaches zero. There is no submit button and nothing to confirm.
6. Lines are allowed to touch at a dot. Two lines meeting at a shared dot is not a crossing and never counts against you — only lines that pass over each other in open space do.
7. Hint takes the dot involved in the most crossings and moves it to a position that is known to work. It costs one move, the same as dragging it yourself.
8. Moves are counted, and par is one move per dot. Beating par earns three stars, but stars are the only thing moves affect — nothing is lost by taking more.
9. Reset puts the current board back to its starting circle. New Puzzle generates a different board for the same level, so a level can be replayed indefinitely.
10. Levels unlock in order and grow from six dots to twenty-three. The later boards have more dots but are deliberately thinned of edges, so they stay readable.

Tips

• Work the outside first. Pick the dots with the fewest connections and drag them clear of the middle — a sparse rim makes the crowded centre far easier to read.
• Follow the red, not your instinct about what looks messy. A board can look chaotic and have only two crossings left, and the red lines will point straight at them.
• Drag slowly and watch the counter rather than dropping and checking. It updates while the dot is still under your finger, so you can find the good position before committing the move.
• When one dot is in a lot of crossings, pull it right out to the edge of the board. Its lines will sweep across everything on the way, and the position that untangles it is usually far from where it started.
• Try to spread dots evenly rather than clumping them. Crossings come from long lines reaching across the board, and even spacing keeps lines short.
• If a level fights you, Reset rather than grinding. The starting circle is the same every time for a given board, so a second attempt with what you now know is usually much quicker.
• Hint is worth using once on the big boards just to see the shape the answer wants to take — it places a dot in a position that genuinely works, and the rest often follows from it.

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