How to play

Draw one circle in a single stroke, with your mouse or your finger, then lift to see your score. There is no trick to it, just a steady hand and a good eye. Take as long as you like on each stroke; the score only cares about the shape, not the speed.

The game fits the best possible circle to your stroke, then measures how far each point sits from that circle. Your score is 100 minus the average gap as a share of the radius, so a perfect circle scores 100%. After scoring, the ideal circle appears in green over your stroke, with a dot at its center, so you can see exactly where your line drifted.

Scores of 90% or better show in green, 70% to 90% in orange, and below 70% in red. A score of 90% earns a Nearly perfect verdict, and 95% or better earns the Inhuman one. Each round stands alone and your best score is not saved, so just draw again and try to beat your last number. If you only tap or draw a tiny dot, the game clears the board and lets you try again.

Size is a choice, not a score. The score judges your circle by proportion, so a big circle and a small one are judged the same way, and you should draw whatever size feels comfortable. After each round, read the overlay instead of just the number: your stroke dims, the ideal circle appears in green with a dot at its centre, and you can see where your line sat inside or outside the perfect shape.

FAQ

How is the score calculated?: The game fits the best possible circle to your stroke, then measures how far each point of your stroke sits from that circle. Your score is 100 minus the average gap as a share of the radius, so a perfect circle scores 100%.
What is the green circle?: After scoring, the game draws the ideal circle in green over your stroke, with a dot at its center, so you can see exactly where your line drifted.
What does avg wobble mean?: It is the average distance, in pixels, between your stroke and the perfect circle. A smaller number means a rounder circle.
What if I only tap or draw a tiny dot?: The game tells you that was more of a dot, clears the board, and lets you try again with a real circle.
Does the game save my best score?: No. Each round stands alone, so just draw again and try to beat your last number.
Can I play on my phone?: Yes. Draw with your finger and the scoring works exactly the same as with a mouse.

Tips

Draw from your shoulder rather than your wrist, and keep your speed steady.
Do not stop and correct yourself halfway round. A smooth, slightly imperfect circle reads as rounder than a wobbly one you kept patching.
If your circles always lean the same way, start the stroke from a different point and see if the lean follows.
When your score stalls, change one thing at a time: your speed, your starting point, or the size of the circle.

How scoring works

The game fits the best possible circle to your stroke using a least squares fit, which picks the centre and radius that sit closest to all of your points at once. It then measures how far each point sits from that fitted circle and averages those gaps. That average gap is your wobble, shown in pixels. Your score is 100 times one minus the average gap divided by the radius, so a perfect circle scores 100.

Dividing by the radius is what makes the score fair across sizes. A big circle and a small circle with the same shape earn the same score, because the wobble is judged against the circle it belongs to. The wobble number itself is raw distance, so the same score on a bigger circle means a bigger wobble in pixels. Compare scores across sizes, but only compare wobble numbers between circles of about the same size. Speed is never scored, only shape, and a stroke with fewer than 12 points counts as a dot.

Score bands: what your number means

Scores of 95 and above earn the Inhuman verdict. The line stays almost on the ideal circle all the way round, with barely a visible drift. Scores from 90 to 95 earn Nearly perfect and show in green: a very steady hand with only small drifts. Scores from 70 to 90 show in orange and earn the Impressive verdict: clearly round, with visible wobbles. Scores from 40 to 70 are Not bad: recognisably a circle, but lopsided or wobbly in places. Below 40, the shape drifts far from any circle, usually from a rushed stroke or a circle drawn too small to control.

Technique: wrist versus arm, speed, starting point

Wrist and arm draw different circles. The wrist pivots in a small arc, which suits small circles but tends to flatten one side, because the wrist runs out of range partway round. The shoulder and arm move the whole hand round the shape, which suits bigger circles and stays steadier through the full turn. Try both and keep whichever one scores better for you.

Speed should be steady and medium. Too fast and the line runs away from you before you can steer it. Too slow and your hand shakes, and you start correcting the line mid stroke, which adds kinks. One smooth motion beats a patched one: the score measures every point against the fitted circle, so a kink counts wherever it sits. Start where your hand feels most comfortable, often the top, and aim to meet your starting point as you close the loop. The game scores the roundness of the line, not whether the ends meet, so an open arc can still score well if it sits on the circle. A mouse lets you see the whole line, while a finger hides the line under your fingertip, so try both.

More tips

Warm up with two or three throwaway circles before you chase a score.
If one side always bulges, rotate your starting point a quarter turn and see if the bulge moves with it.
Watch the line, not your hand. Looking at where the line is going keeps it on the circle.

Related guides

Want to go deeper? Read the Circle Master scoring guide for the scoring formula in detail, and Click Frenzy and Circle Master tips for the companion clicking game and more circle technique.

Circle Master