# Fill One: Line Brain Puzzle

> Fill One: Line Brain Puzzle (iPhone/iPad app by Nhung Thi Lam Thi.)

- Source: https://appshunter.io/ios/app/fill-one/id6759598128 (this page in markdown: same URL + `.md`)
- Developer: [Nhung Thi Lam Thi](https://appshunter.io/developer/1877108777)
- Category: Games, Casual, Puzzle
- Price: Free
- Age rating: 4+
- Requires: iOS 13.0 · 80 MB
- Languages: English
- Released: 2026-02-25
- Data updated: 2026-05-15
- User reviews in markdown: https://appshunter.io/ios/app/fill-one/id6759598128/reviews.md

## What is Fill One?

Looking for a simple yet deeply addictive way to sharpen your mind? One Stroke Master brings you the most comprehensive brain-training experience with a staggering 3,200 levels to conquer. Best of all? It’s completely free to play!

WHY YOU'LL LOVE ONE STROKE MASTER:
Whether you're on your daily commute or winding down before bed, spending just a few minutes a day with this puzzle will help keep your brain active and focused.

HOW TO PLAY:
The rule is elegantly simple: Fill all the blocks using just one continuous line. Don't worry about getting stuck—free hints are always available to help you navigate through the most complex patterns.

CHALLENGE YOUR LIMITS:
Progress through four escalating difficulty tiers:

Beginner: Get the hang of the mechanics.

Expert: Start testing your logic.

Professional: For those who love a serious challenge.

Master: "Impossible" difficulty for true puzzle geniuses.

THE MATHEMATICAL ORIGIN:
Inspired by the famous "Seven Bridges of Königsberg" problem from the 18th century, one-stroke puzzles are more than just games—they are mathematical exercises proven to boost work efficiency and prevent mental aging.

GAME FEATURES:

3,200 Levels: The largest collection of one-line puzzles on the store.

4 Difficulty Modes: Tailored for all skill levels.

Free Hints: Never feel frustrated; help is just a tap away.

Minimalist Design: Clean, distraction-free UI to help you focus on the logic.

Offline Play: No internet? No problem. Train your brain anywhere, anytime.

Step into the world of logic and see if you have what it takes to master all 3,200 levels. Download One Stroke Master today!


## Version history (last 3 releases)

### 1.4 — 2026-04-09

Optimized Game Features

### 1.2 — 2026-03-26

update game content.

### 1.0 — 2026-02-25

No release notes.

## More apps by Nhung Thi Lam Thi

- [Gravity Trial:Plant Jump](https://appshunter.io/ios/app/gravity-trial/id6760386779)
- [Home Guardian Puzzle](https://appshunter.io/ios/app/home-guardian-puzzle/id6760387058)
- [Ring Link Master](https://appshunter.io/ios/app/ring-link-master/id6760387212)
- [Morph Path:Hue Line](https://appshunter.io/ios/app/morph-path/id6760387216)
- [Planet Maze Rolling](https://appshunter.io/ios/app/planet-maze-rolling/id6761356697)

All apps by Nhung Thi Lam Thi: https://appshunter.io/developer/1877108777

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-05-15.*