One Line

Draw the whole figure in a single unbroken stroke, covering every line exactly once. Tap dot to dot to trace it. Solve as many shapes as you can in 90 seconds.

How to play

A figure of dots and connecting lines appears. Tap a dot to begin, then tap a dot joined to it to trace that line; the line lights up as drawn.

Keep moving from dot to dot, drawing one new line each step, until every line is covered. You may pass through the same dot many times, but each line can be drawn only once.

Where you start matters. Some figures can begin anywhere; others can only be completed if you start at one of two special dots, so if you get stuck with lines still grey, tap Reset and try starting somewhere else.

Finish a figure to score and a fresh one appears at once. You have 90 seconds — solve as many as you can.

Tips & strategy

There is one rule that decides every puzzle: count how many lines meet at each dot. A dot with an odd number of lines is an odd dot, and a figure is only drawable in one stroke when it has either zero or exactly two odd dots. Spotting the odd dots first tells you everything about where to begin.

When a figure has two odd dots, you must start at one of them and you will finish at the other. Starting anywhere else is the single most common reason a solve dead-ends with one stray line left, so train your eye to find those two odd dots and begin there every time.

When every dot is even, you can start wherever you like, but you must end back at your starting dot, so the stroke forms a closed loop. For these, the danger is splitting the figure: avoid drawing a line that strands a clump of untraced lines you can no longer reach, and save bridging lines between dense areas for when you actually need to cross over.

In the timed mode, glance at the whole shape before your first tap rather than diving in. A second spent locating the odd dots almost always beats a hopeful start and a forced reset, and once you trust the odd-dot rule you will solve most figures on the first attempt.