One Stroke
Trace each figure without lifting the pen or repeating a line. A few figures cannot be traced at all.
Use Tab to pick a point and Enter or Space to go there.
How to play
Trace the figure without lifting your pen and without going over any line twice. Tap a starting point, then drag along the lines (or tap the next point) to move on. To step back, tap the previous point or press Undo. Some figures cannot be traced at all; when you think so, press "Cannot be traced".
Learn more
The clue is the number of lines at each point. At a point in the middle of your path, every arrival pairs with a departure, so a point with an odd number of lines (an odd point) can only be where you start or finish. With 0 odd points you can come back to where you began, with 2 the path runs between them, and with any other number the figure cannot be traced. This is the idea Euler used for the Konigsberg bridges.