How the score works
Your line is split into 180 directions around the dot, and the distance from the dot to the line, the radius, is measured in each one. In a perfect circle every radius is the same. The spread of the radii (their root mean square deviation) is taken as a share of the average radius, and score = 100 − 3 × that share in percent. A circle whose radius wobbles by about 2% scores 94.
If the dot is not at the center of your circle, one side's radius is longer than the other's, so the score drops. The score therefore rewards both roundness and centering. Because the radii are sampled evenly by direction, drawing some parts faster than others does not change the score.
Rules
- One full loop around the dot finishes the drawing. Clockwise and counterclockwise both count.
- Passing too close to the dot ends the attempt.
- Lifting your finger, reversing direction, or taking longer than 15 seconds also ends it.
Tips
- Swing from the elbow or shoulder instead of the wrist for a smoother line.
- Going too slowly makes the line shaky. Keep a steady speed and do it in one go.
- Focus on meeting your starting point at the same distance in the last stretch.
- On a phone, use as much of the screen as you can.