Trace Once

A glowing one line puzzle game: draw every picture in one stroke, without lifting your finger. 300 puzzles in 10 chapters, with double lines, one-way lines, a daily puzzle and Rush.

Trace Once is a one line puzzle game played online in your browser: draw every picture in one stroke, without lifting your finger and without drawing any line twice. Each picture is made of points and lines, from an ice cream cone to stars, houses and knots, and a gold thread lights it up as you trace.

There are 300 handmade puzzles in 10 chapters, from First lines to the Grand finale. New ideas arrive along the way: double lines that must be drawn twice, one-way lines with arrows, curved lines, junction dots where you may turn, and bridges where one line passes over another without joining it. On top of the levels there's a new daily puzzle every day (the same for every player, 366 in all) and Rush, a race against the clock.

If you like Sudoku, Nonograms or the old pencil puzzle of drawing a house without lifting the pen, Trace Once is a calm, glowing take on that idea.

How to play this one line puzzle game

Press on any point of the picture and drag along its lines. Each line you cover lights up. Cover every line in one stroke and the picture is solved; lift your finger or mouse button too early and the drawing resets, so just start again.

Went the wrong way? Drag back along the line you just drew to take it back. Double lines, marked with a ×2 badge, have to be drawn twice, once along each strand. Lines with arrows can only be drawn the way the arrows point. Where lines cross on a bridge they don't join: you can only turn where lines meet at a dot.

Solve a picture on your first stroke without a hint for 3 stars. Stuck? A hint shows the points where you can start; a second hint traces the whole path.

Features

• 300 one line puzzles in 10 chapters, with a level map to replay any picture you've drawn
• Double lines (×2), one-way lines, curves, junction dots and bridges at crossings
• A daily puzzle, the same for everyone that day, with a streak to keep going
• Rush: draw as many random pictures as you can; every solve adds time to the clock
• Two-step hints: first the starting points, then the full path. You earn more as you clear new levels
• Stars for solving on the first stroke, without a hint
• 6 languages: English, Spanish, French, German, Portuguese and Japanese
• Plays in portrait or landscape, with progress saved in this browser

Tips

• Count the lines at each point. If two points have an odd number of lines, start at one of them and you'll finish at the other.
• A double line counts twice, so it changes which points are odd.
• Follow the arrows backwards from where they end to see where a one-way picture has to start.
• Leave the long outer lines for last: they're the easiest to come back along.
• Don't turn on a bridge. Only a dot is a place to change direction.

FAQ

How do you solve a one line puzzle?

Find where to start. A picture can be drawn in one stroke when every point has an even number of lines, or when exactly two points have an odd number; then you start at one odd point and end at the other. Trace Once's first hint shows those starting points for you.

What does draw in one stroke mean?

It means drawing the whole picture in one continuous line: you never lift your finger or pen, and you never go over the same line twice (unless it's a double line, which you draw twice).

How many levels are in Trace Once?

300 puzzles in 10 chapters, plus a daily puzzle and the endless Rush mode.

Is there a daily puzzle?

Yes. Every day there's a new picture, the same for all players, and solving it each day builds your streak.

Can I play Trace Once online without downloading?

Yes. It runs in your browser on a computer, phone or tablet, with touch or a mouse, and saves your progress in that browser.