Perfect Circle Challenge

How to Play?

The rule is simple: Draw a circle around the center dot using your mouse, trackpad, or finger. Try to make it as perfectly round as a machine would!

The Scoring Algorithm Explained

If you find it hard to get a high score, here's how we judge your circle. We analyze three key metrics:

1. Radius Consistency: We calculate the distance from every point you drew to the center. For a perfect circle, all distances should be identical. Your score is based on the standard deviation of these distances.
2. Smart Trimming: Humans naturally shake when starting or stopping a line. To be fair, our algorithm automatically ignores the first 10% and last 10% of your stroke, evaluating only the smoothest middle part.
3. Closure Detection: You don't need to connect the end point to the start point perfectly. As long as you draw more than 300 degrees (almost a full loop), it counts as a closed circle.

Why can't I get 100%?

• Pixel Limits: Screens are made of square pixels. Mathematically, a "perfect circle" cannot exist on a pixel grid.
• Hand Tremors: Even surgeons have microscopic hand tremors. Mice sensors pick these up.
• Input Devices:
  • 🖱️ Gaming Mice: Usually easier to control (85-98%).
  • 👆 Touchscreens: Great for circular motion. Many world records are set on iPads.
  • 💻 Trackpads: The "Hard Mode". Scoring over 80% here is impressive.

Tips for High Scores

1. Speed Matters: Don't draw too slowly. Slow movement amplifies hand jitters. A confident, fast stroke is usually smoother.
2. Use Your Wrist: Anchor your elbow or forearm, and use your wrist as the pivot point of a compass.
3. Look at the Center: Focus your eyes on the center dot and use your peripheral vision to guide the cursor, rather than staring at the cursor itself.