One-line puzzle

One line sounds simple until it has to cover everything.

Threadline turns a familiar one-line puzzle idea into a daily iPhone habit: start at 1, reach the knots in order, and leave no cell behind.

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Threadline share image showing the daily puzzle app and path puzzle art.
The rule is easy to explain: draw one continuous route. The board makes the route matter.

Why the line has to stay clean

A good Threadline route feels obvious after it is solved. Before that, every bend is a small bet about what space will still be reachable later.

No broken paths The route has to stay connected from the first knot to the last. If the thread jumps, the solve is invalid.
No double-backs Each square is used once, so you cannot patch a mistake by crossing back through a cell you already claimed.
No throwaway spaces The final path must cover the whole grid. A small isolated pocket is usually the clue that the route needs to change.

A one-line solve in four checks

Start Begin at knot 1 and look for the first turn that keeps the grid open.
Order Reach each numbered knot in sequence, not just whichever one is closest.
Space Keep corners and narrow corridors reachable before the route closes them off.
Finish End only when the final numbered knot is also the final unused cell.
Path puzzle See the broader route-finding logic behind each daily board. Daily logic puzzle Read the daily-habit version of the Threadline pitch. Watch short solves Use the live Reels page when you want the hook in motion. Free daily puzzle app Share the broader daily-app page with people looking for a new puzzle habit. iPhone puzzle game Use the iOS-first landing page for App Store and puzzle-player context. No ads puzzle app Point privacy-minded players to the no ads, no account version of the pitch.

One-Line Puzzle FAQ

Is Threadline only one line?

Yes. The solve is one continuous thread from start to finish, and every cell must be used exactly once.

Does the web demo use the same rule?

Yes. The browser demo uses the same core rule so you can test the feel before opening the iPhone app.

Is there a new puzzle every day?

Yes. The iPhone app gives you a fresh daily puzzle and turns solved days into a yearly Tapestry.

Try the one-line puzzle today

Threadline is free on iPhone, with no ads, no account, and no tracking.

Open on App Store