About Threadline
Threadline is a free browser logic puzzle in the single-line path family - the same idea as LinkedIn's Zip and the classic Numberlink and Hamiltonian-path puzzles - with one rule no other version has: thread tension. Every puzzle comes with a bend budget, shown as a meter from the first move. Straight moves are free, but each change of direction spends a bend, and once the budget is spent the thread can only continue straight. Try to bend it anyway and it snaps back to the last number you reached, the cells clear in reverse order, and that segment's bends are refunded. Reading the grid is not enough; you have to read the thread. There are two modes. The Daily Challenge is one 6x6 grid per UTC day, generated from the date itself so every player in the world gets the identical grid with the same numbers, walls, gate and budget. It is scored on solve time against a 90-second par with a flat penalty per mistake, your first solve of the day posts to the daily leaderboard, and a Wordle-style text card is ready to share when you finish. Completing the daily keeps a streak alive that is saved to your account. The Endless Ladder gives every grid its own three-minute clock and climbs from 5x5 to 6x6, 7x7 and finally 8x8 grids as you clear three puzzles at each size, with two extra layers on top of tension: knots, cells the line must cross twice, straight through each time, once in each direction; and fog, where the upcoming numbers stay hidden until you reach the one before them. Each clear is worth more on a bigger grid, faster clears earn a bonus, and knot and fog puzzles carry multipliers. Threadline has no hints, no currency, no ads and no purchases. It is playable without an account, works on phones, tablets and desktops with full keyboard support, honours your reduced-motion setting, and needs nothing downloaded.
How to Play Threadline
Press on the 1 and drag one continuous line through every cell of the grid, reaching the numbers in ascending order and finishing on the highest one. You can never cross a white wall bar, and the cell with the cyan arrow can only be entered from the side the arrow points in from. Every time your line changes direction it spends one bend from the tension meter above the board. At two bends left the thread thins and brightens, at one it trembles and the meter turns amber, and a bend attempted at zero snaps the thread back to the last number you reached, refunding that segment's bends. Straight moves are always free. Tap the last cell or press the undo button to step back. The grid is solved the moment every cell is filled with the numbers in order.
Threadline Tips and Strategy
- Read the whole grid before you touch it: count the bends the numbers force on you, compare that with the meter, and you will know how much slack you really have
- Straight runs are free. Only a change of direction spends thread, so a long sweep along an edge costs nothing while a zig-zag through the middle burns the budget fast
- The gate arrow points into the cell from the only side you may enter. Plan the approach to that cell first and let the rest of the route wrap around it
- When the meter reads one bend left and the thread starts to tremble, stop and look for a straight line to the next number - a bend at zero snaps you back to your last number
- A snap is not a restart. The thread only unravels to the last number you reached, and the bends that segment spent come back, so you get a genuine second attempt at that stretch
- Knots must be crossed twice, straight through each time, once horizontally and once vertically - route the first pass so the second one lines up with the numbers still to come
- In fog, only the next number shows. Cover the corners early, because a hidden number tucked into a corner is the one that traps you at the end
- The daily board scores your first solve only, so a clean 60-second run with no mistakes beats a frantic 30-second one with three
Threadline FAQ
Is Threadline free to play?
Yes. Threadline is completely free with no ads, no in-app purchases and nothing to download. It runs in any modern browser on phone, tablet or desktop, and the daily grid works offline once the page has been cached.
How is Threadline different from Zip or Numberlink?
The base rule is the same one-line-through-every-cell idea, but Threadline adds thread tension: every puzzle has a bend budget, each change of direction spends one bend, and a bend attempted with nothing left snaps the thread back to your last number. The endless mode also adds knots, which the line must cross twice, and fog, which hides the upcoming numbers until you reach them. Every puzzle also has one gate cell that can only be entered from the marked side.
Does everyone get the same daily puzzle?
Yes. The daily grid is built from the UTC date by a deterministic seeded generator, so every player on a given day gets exactly the same numbers, walls, gate and bend budget. That is what makes the daily leaderboard a fair race: everyone solved the same grid.
How is the daily score calculated?
You start from 10,000 points against a 90-second par. Every second under par adds 60 points with no cap, every second over par costs 40, and each mistake, including a snap, costs a flat 400. The score never drops below 200, so a slow, careful solve still posts a real number. Only your first solve of the day counts on the leaderboard.
What counts as a mistake?
Only an actual rule break: crossing a wall, reaching a number out of order, entering the gate cell from the wrong side, crossing a knot the wrong way, or snapping the thread by bending at zero budget. The move is rejected on the spot and the counter goes up by one. Drawing yourself into a dead end is not a mistake - nothing is rejected, you simply notice and undo.
What happens when the thread snaps?
The path unravels back to the last numbered cell you reached, those cells clear in reverse order, and the bends that segment spent are refunded to the budget. It counts as one mistake, but it never resets the whole puzzle, so it is a second attempt at that stretch rather than a restart.
How does the Endless Ladder work?
Every grid gets its own three-minute clock, and the run ends when one runs out or you quit. You start on a 5x5 grid and move up to 6x6, 7x7 and 8x8 after clearing three puzzles at each size. Bigger grids are worth more per clear, beating each grid's par time earns a speed bonus, and puzzles with knots or fog multiply the clear's value. Your total across all clears is the run score, and the biggest grid you cleared is your level.
Can I play with a keyboard?
Yes. The arrow keys extend the path one cell at a time, Backspace undoes one step, and Escape pauses. Every cell announces its state to screen readers, the tension meter always shows a numeric bends-left label, and reduced motion removes the tremor and snap animations entirely.
