One Stroke

One Stroke: The Free One-Line Puzzle Game That Never Lets You Cheat the Path

One Stroke is a free browser puzzle game with one simple rule: connect every line on the board using a single continuous stroke, never lifting your finger, and using each line exactly once. There's no download and no account — open the page and you're tracing your first puzzle in seconds. Lift your finger before you've used every line and the stroke breaks, forcing a restart, so every solve has to be planned, not stumbled into. Play through 100 hand-tuned Classic levels, take on a Daily Challenge that's the same for every player each day, or push an Endless run as far as your streak can carry it — free, right now, at Game CMB.

What Is One Stroke?

One Stroke is a tracing puzzle built on a real branch of math — Eulerian paths, the same idea behind the classic "draw this shape without lifting your pen" party trick. Every level is a web of nodes connected by lines. Your job is to drag a single unbroken stroke through the entire board, crossing every line exactly once, without ever lifting your finger until the whole thing is solved. Cross a line twice, skip one, or lift your finger too early, and you haven't solved it — you've broken it.

What makes that rule interesting instead of just restrictive is that every puzzle in One Stroke is mathematically guaranteed to be solvable before it's ever shown to you — there's no such thing as an impossible board. That means every failure is genuinely on you: a plan that didn't account for the whole shape, or a finger lifted a half-second too early. The game runs entirely in the browser on HTML5 Canvas, with glowing nodes, a live particle trail following your stroke, and a dark neon look that works identically on a phone or a desktop — no install, no plugin, no loading screen.

How to Play One Stroke

1. Look at the board before you touch it. Every solvable puzzle has either zero or exactly two "odd" junctions — points where an odd number of lines meet — and if there are two, your stroke has to start on one of them and end on the other.
2. Press down on a node to start your stroke. This is the one moment you're allowed to lift your finger again — before you've begun.
3. Drag through the lines, one after another, connecting each node to the next along an existing line. A ghost trail and particle glow follow your finger as you go.
4. Use every line exactly once. Dragging back over a line you've already used, or trying to cross a line that isn't there, counts as a mistake — the board flashes red, but your stroke isn't broken, so you can keep going.
5. Never lift your finger until the puzzle is fully solved. Lift early — even by accident — and the stroke breaks, the puzzle restarts, and you're back at the beginning of that attempt.
6. Ask for a hint if you're stuck. One Stroke's hint system is built to never suggest a move that would trap you — it's calculated the same way the game itself guarantees every puzzle is solvable, so a hint is always safe to take.
7. Finish the board and see your score — built from your completion time, and how few mistakes, hints, and restarts it took to get there.
8. Move on to the next level, the Daily Challenge, or an Endless run — three separate ways to keep playing once the board in front of you is solved.

Key Features

• 100 hand-tuned Classic levels that climb steadily in size and complexity, unlocking one at a time as you clear each puzzle.
• Every puzzle is mathematically guaranteed solvable before it's ever generated for you — there is no such thing as an impossible One Stroke board.
• A genuinely safe hint system that always points to a move that keeps the puzzle solvable, never one that quietly sets you up to fail two moves later.
• Instant dead-end detection — if a wrong sequence of moves ever makes the puzzle unsolvable from where you are, the game tells you immediately instead of letting you wander a board that can't be finished.
• A Daily Challenge at a fixed difficulty, identical for every player on a given day, so the leaderboard is a genuine apples-to-apples comparison rather than everyone attempting a different puzzle.
• An Endless mode that starts where the Classic levels leave off and keeps growing in size the longer your streak survives.
• A streak that rewards precision, not just progress — solving a puzzle with zero mistakes, hints, or restarts grows your Endless streak; a messy clear costs you one instead of wiping it out.
• A score built from more than just "did you finish" — your completion time and how clean the run was (mistakes, hints, restarts) all factor into the final number, with a real bonus for a flawless run.
• Three separate leaderboards — Classic (per level), Daily Challenge, and Endless — each showing the global top 10 plus exactly where you rank.
• Zero downloads, zero accounts — fully playable in any modern mobile or desktop browser, with a nickname the only thing you need to type to appear on a leaderboard.

Why One Stroke Is So Addictive

Most tracing or connect-the-dots puzzles let you fumble your way to a solution through trial and error — drag around long enough and you'll eventually stumble onto the right order. One Stroke removes that safety net the moment you lift your finger: an unfinished stroke doesn't pause, it breaks. That single rule turns every board into something you have to actually read before you touch it, because a mid-puzzle "let me start over and think" costs you the whole attempt, not just a few seconds.

That tension is exactly what keeps a level from feeling solved too easily. The early boards teach you to spot the two endpoints and trace a rough plan in your head; by the time you're a few dozen levels in, spotting that plan at a glance becomes its own small rush — the moment right before you touch the first node, when you can already see the whole path in your mind, is the actual hook. Endless mode sharpens that further: since your streak only grows on a genuinely clean solve, going faster isn't the goal past a certain point — going cleanly is. And because the Daily Challenge hands every single player the exact same puzzle, there's a built-in reason to come back every day even after you've cleared every Classic level: today's board is the one thing on the leaderboard that resets to a level playing field for everyone, every 24 hours.

5 Tips to Get Better at One Stroke

1. Find the two odd junctions before you touch the screen. Any solvable puzzle with two of them forces your stroke to start on one and end on the other — spotting them first tells you exactly where to begin instead of guessing.
2. A wrong move isn't a restart — a lifted finger is. Crossing the wrong line just costs you a mistake point and a red flash; you can keep dragging and recover. It's almost always better to keep going than to lift your finger and start the whole puzzle over.
3. Save your hint for when you're actually stuck, not the first tricky junction. Since a hint never leads you into a dead end, one hint used at the right moment is worth far more than three burned out of early impatience.
4. In Endless mode, slow down once your streak matters more than your time. A flawless clear grows the streak; a rushed, mistake-filled one only costs you a point off it — past the first few puzzles, precision compounds faster than speed does.
5. Play the Daily Challenge every day, even after finishing all 100 Classic levels. It's a fixed difficulty shared by every player, so it stays the fairest way to measure yourself against the rest of the board — not just against your own last run.

One Stroke FAQ

Is One Stroke free to play?

Yes. One Stroke is completely free to play in your browser on Game CMB, on desktop or mobile, with no download, purchase, or account required.

What is the goal of One Stroke?

Each puzzle is a set of nodes connected by lines. The goal is to drag a single continuous stroke that crosses every line exactly once, without ever lifting your finger, until the entire board is connected.

What happens if I lift my finger before finishing?

Lifting your finger before the puzzle is fully solved breaks your stroke and restarts that attempt from the beginning. Crossing a wrong or already-used line, on the other hand, only counts as a mistake — it doesn't end your attempt, so you can keep going.

Are the puzzles always solvable?

Yes. Every One Stroke puzzle is generated and mathematically verified to be solvable before it's ever shown to you, using the same graph theory behind the classic "draw this without lifting your pen" trick. There is no such thing as an impossible board.

Can I get hints, and will a hint ever trap me?

Yes, every level has a hint button. One Stroke's hints are calculated to always point to a move that keeps the puzzle solvable — a hint will never set you up for an unavoidable dead end later in the puzzle.

What is the Daily Challenge?

The Daily Challenge is a single puzzle at a fixed difficulty that's identical for every player on a given day. Its own leaderboard resets daily, so it's a fair, apples-to-apples way to compare your solve against everyone else playing that same day.

How does Endless mode work?

Endless mode starts where the 100 Classic levels leave off and keeps generating progressively larger puzzles for as long as you keep solving them. Your streak grows only when you clear a puzzle perfectly — no mistakes, hints, or restarts — and a messy clear costs you one point off the streak rather than resetting it to zero. Your cumulative score for the run is saved even if you stop partway through.

How is my score calculated?

Your score for a puzzle is based on how quickly you completed it and how clean the run was — fewer mistakes, hints, and restarts all raise your score, and a completely flawless solve earns a real bonus on top.

Do I need an account to play or save my score?

No account is required. Your progress is tracked automatically in your browser, and you only need to type a nickname when you want a run's score to appear on a leaderboard.

Does One Stroke work on mobile?

Yes. One Stroke is fully responsive and playable on mobile browsers, with the same drag-to-trace controls as desktop.

Is there a leaderboard?

Yes — three of them. One Stroke tracks separate leaderboards for Classic levels (per level), the Daily Challenge, and Endless mode, each showing the global top 10 plus your own rank.

Ready to Trace Your First Path?

The board is waiting, and so is the moment right before you touch the first node — when the whole path either clicks into place or it doesn't. Play One Stroke now on Game CMB — free, instant, no download required.