How it works
Shape Echo trains spatial working memory and size constancy — the everyday skill of holding an object's position, scale and tilt in mind after it's gone, rather than while it's still in view. Each round flashes a single shape on a square stage for a couple of seconds, then hides it completely. From there you rebuild it from nothing: drag anywhere on the stage to move your shape, and use the Size and Rotation sliders below it to match what you remember, before locking in your answer.
Scoring is split into three components, weighted 40% position, 40% size and 20% rotation. Position is measured as the distance between your shape's center and the target's, size compares the two shapes' areas rather than raw width, and rotation compares angles honestly — a rectangle or ellipse looks identical every 180°, so a 178° guess against a 2° target is judged as roughly 4° off, not 176°. An equilateral triangle repeats every 120° for the same reason. The three components combine into an accuracy percentage, which converts to a round score out of 10 on the site's usual curve.
Difficulty adds shape types and removes forgiveness together: Easy is rectangles only with no rotation to worry about, Medium adds ellipses and tilt, and Hard adds triangles with only 1.5 seconds to look before it vanishes.