Puzzle · One stroke

One Line

一筆畫

Start at GO and cross every tile once — without ever lifting your finger. Try it right here, no download needed.

Level 0 · warm-upDrag or tap

650+
Levels, every one solver-verified
1
Unbroken stroke per board
0
Signal required to play
4s
Roughly how long level 1 takes
Rules

Three rules, and that's the whole game

No timer, no tutorial to sit through. Look at the shape, find the route, draw it.

01

Start at GO

Every board marks its starting tile. Put your finger there and begin.

02

Cross every tile once

Move up, down, left or right. Each tile takes exactly one visit — no doubling back over your own line.

03

Never lift your finger

It has to be one unbroken line. Stuck? RETRY resets the board instantly and costs you nothing.

Features

Easy to pick up, easy to put down

A board takes about a minute. The good part is the click in your head right before you draw.

650+ verified boards

Every level is run through a solver before release, so you are never stuck on an impossible one.

A hint, only if you want it

HINT lights the next tile on the path — enough to unstick you, not enough to spoil the solve.

Boards that draw pictures

Push past the early levels and tiles start forming numerals and shapes. Level 633 spells out its own number.

Works with no signal

No account, no connection. Play on a flight, underground, or in a queue — free, all of it.

Screens

Level 25 looks nothing like level 656

Pick a screen on the right to see it full size.

One Line gameplay
Ranking

The leader is on level 79

Which sounds catchable, right up until level 40. The board tracks the highest level each player has cleared.

RankingTop players
  1. 1玩家 7B9F79
  2. 2玩家 2CCD56
  3. 3玩家 808950
  4. 4玩家 13BC26
  5. 5← your slot?
  6. 6玩家 E7B311
  7. 7玩家 955A7

How the board works

Your position is simply the highest level you have finished — no points, no stars, no daily streak to protect. Clear one more board and you move up. Miss a week and nothing is taken away.

Sample board shown. Live standings appear in-game.

Ready to draw the first line?

Free to download, free to play, and level 1 takes about four seconds.

© techbeast. All rights reserved.

Privacy Policy

We collect only what the game needs to run. Here is exactly what that is, what we do with it, and how to take it back.

Last updated: 6 August 2026

Welcome to One Line (the "Game"). This policy covers the iOS and Android apps as well as the web and Facebook Instant Games versions. By playing, you agree to what is described here.

01What we collect

So the game runs properly and your progress records correctly, we may collect the following:

CategoryWhat it is and why
Device infoModel, OS version, language setting and an anonymous device identifier — used for compatibility and performance tuning.
Game progressHighest level cleared, levels completed and hints used — used for the ranking board and progress sync.
Public account dataIf you sign in with a platform account, we receive the public nickname and avatar you authorise, shown only on the ranking board.
Usage behaviourAnonymised statistics such as session length and which levels get retried most — used to tune difficulty.
DiagnosticsCrash and error logs used to fix problems and improve stability. These contain nothing that identifies you personally.

We do not collect your real name, phone number, home address, contacts, precise location or financial details — unless you choose to include them when writing to us.

02How we use it

  • Running and maintaining the game, including the ranking board and cross-device progress sync.
  • Analysing anonymised statistics to balance level difficulty and improve the hint system.
  • Detecting and fixing crashes, stuck boards and impossible results.
  • Replying to questions and suggestions you send through the support address or contact form.
  • Serving content and handling transactions, if your version includes ads or in-app purchases.

We do not sell your personal data, and we do not pass it to third parties unrelated to running the game for marketing purposes.

03Third-party services

The game integrates the following kinds of third-party services, each of which handles data under its own privacy policy:

  • Platform services — Apple App Store, Google Play and Meta (Facebook Instant Games), for sign-in, distribution and platform leaderboards.
  • Analytics — anonymised statistics that tell us which levels are too hard or too easy.
  • Ads and in-app purchases — where included, these providers may process advertising identifiers and transaction records.

We recommend reading each platform's own privacy policy for the full picture.

04Storage and security

We use reasonable technical and organisational measures to protect your data against unauthorised access, disclosure, alteration or destruction. Data travels over encrypted connections and server-side access is limited to the people who need it.

Progress and ranking records are held in the cloud only for as long as the service needs them. If you ask us to delete them, we remove or anonymise the relevant records within a reasonable period.

05Children's privacy

The game is suitable for a general audience, and we do not knowingly collect unnecessary personal information from children under 13. If you are a parent or guardian and find that your child has provided personal data without consent, contact us using the details below and we will remove it promptly.

06Your rights and choices

  • Turn off personalised advertising or reset your advertising identifier in your device settings at any time.
  • Ask us to provide, correct or delete the game data associated with you.
  • Unlink the game from your platform account at any time, which stops ranking sync.
  • Where local law grants further rights (for example the EU GDPR or California's CCPA), we will honour them accordingly.

To exercise any of these, write to support@techbeast.co.

07Policy updates

We may revise this policy from time to time. When we do, the date at the top of this page changes; for significant changes we will also notify you in-game or by another suitable method.

Still have questions?Write to us — we usually reply within two working days.

Contact us
© techbeast. All rights reserved.

Stuck on a level, or stuck on a bug?

Either way, tell us. Bug reports, level feedback and partnership notes all land in the same inbox.

Send us a message

Fill this in and hit send. Your message goes directly to our support inbox, and this site does not keep a separate copy.

We use these details only to read your message and reply to you.

Support address

support@techbeast.co

Response time

Monday to Friday, usually within two working days. Holidays may be slower, but every message gets read.

Think a level is impossible?

Send the level number and a screenshot. Every board is machine-verified before release, so if one really is broken we want to know fast.

Data questions

Want your progress deleted, an account unlinked, or just to know how we handle data? Check the privacy policy, or ask us directly.

FAQ

Six things people ask us most

01Does One Line cost anything?+
Free to download and free to play. Every level is open from the start — you don't pay to unlock anything.
02I'm certain this level can't be solved.+
Every board is checked by a solver before it ships, so a solution does exist. Try RETRY and start from a different corner — most "impossible" levels just need a different opening direction. If you still can't crack it, send us the number and we'll look.
03Why is the next level locked?+
You can preview any upcoming board, but you have to clear the previous level to play it. It keeps the difficulty curve honest.
04Will my progress survive a new phone?+
If you've linked a platform account, sign in with the same one and your progress comes with you. Playing as a guest keeps everything on the device only, so link an account before you switch.
05Can I play without a connection?+
Yes. The levels live on your device, so flights and underground trains are fine. Your ranking updates the next time you're online.
06Interested in press or a partnership?+
Very welcome. Email the support address with a short note about what you have in mind and who to talk to — we'll reply, and we can send a press kit.
© techbeast. All rights reserved.