How to Play One Stroke
One Stroke is a free one-line drawing puzzle you play right in your browser — no download and no sign-up. Each of the 200 hand-built levels shows a shape made of connected lines, and your job is to trace every single line in one unbroken stroke: start on any dot, drag through the whole figure, and never lift your finger or go back over a line you have already drawn. It is the classic "draw it without lifting the pen" brain teaser — a real Eulerian-path puzzle dressed up as a calm little doodle.
How to play
Tap or click a dot to begin, then drag along the lines. Each line lights up once you have drawn it, and the counter at the bottom shows how many of the shape's lines you have covered so far. Cover all of them in a single continuous path and the level is solved. Stuck? Lift off and the board resets, so you can try a different starting point — some shapes can only be finished if you begin on exactly the right dot.
Why some shapes cannot be drawn in one stroke
The rule behind every level is nearly three hundred years old. Count the lines meeting at each dot. If every dot has an even number of lines, a solution exists and you may begin anywhere, finishing back where you started. If exactly two dots have an odd number of lines a solution still exists, but you have to begin on one of those two odd dots and you will always finish on the other. If four or more dots are odd, no unbroken stroke can cover the figure at all. Every level here is built to satisfy that rule, so a level that feels impossible is never unfair — it only means you opened from the wrong dot. Counting the odd dots before you draw is the quickest way to find the right starting point, and it turns the later levels from guesswork into something you can reason about.
Tips to solve any level
Two quick rules crack almost every board. First, count the lines meeting at each dot: a figure can be drawn in one stroke only when zero or exactly two dots have an odd number of lines — and when there are two, you must start on one of them and finish on the other. Second, plan your exits and don't burn the only line out of a dot too early, or you'll strand yourself. Start simple, and by level fifty you'll be reading these paths at a glance.
Questions people ask
Do I need to install anything? No. One Stroke runs entirely in your browser on phone, tablet or desktop, with no download and no sign-up.
Is every level actually solvable? Yes. Each of the 200 shapes is built around a valid single-stroke path, so there is always at least one route that covers every line exactly once.
What if I get stuck? Tap the eye button to preview the solution, or the reset arrow to clear your line and try a different opening dot. Neither costs you anything, and you can replay a level as often as you like.
Can I jump to a particular level? Yes. The menu button in the top-left corner opens the level picker.
Does it work with a mouse as well as a finger? Yes. Drag from dot to dot either way; the line follows your pointer and snaps to the next dot when you release.