How is area overlap calculated?

The game rasterizes both shapes to a pixel grid and divides the number of shared "filled" pixels by the union of both shapes' pixels — a standard Intersection over Union (IoU) score.

Does position matter or just shape accuracy?

Both matter — the game compares shapes at their actual canvas positions, so you need to remember roughly where the shape appeared.

What overlap score is considered excellent?

Above 80% overlap is excellent. 60–80% is solid. Below 50% means the shape category was remembered but detail was lost.

Can You Match This Shape?

Can you match the shape after memorizing it for just 3 seconds? A polygon or irregular shape flashes on screen, then you must redraw it from memory. Scoring is based on area overlap between your drawing and the original — the higher the overlap percentage, the better your spatial recall. Simple polygons are manageable; multi-pointed irregular shapes will test the limits of your visual working memory.

How to Play

A shape displays for 3 seconds — memorize its size, proportions, and position.
When the shape disappears, draw it freehand on the canvas.
The original shape reappears as an overlay.
Your score is the percentage of area overlap between your drawing and the target.

Why It's Hard

Visual working memory for shapes is limited to roughly 3–4 distinct features simultaneously. You'll remember a shape's general class (triangle, blob) but forget precise edge angles and proportions. The result is a "gist" reproduction — correct in category but systematically smoothed and simplified compared to the original.

Tips

1Count the number of corners and silently track their approximate positions as you study.
2Focus on the overall bounding box first — getting the aspect ratio right improves overlap dramatically.
3Draw the most distinctive feature first (a sharp spike, a flat base) as your spatial anchor.

FAQ

How is area overlap calculated?: The game rasterizes both shapes to a pixel grid and divides the number of shared "filled" pixels by the union of both shapes' pixels — a standard Intersection over Union (IoU) score.
Does position matter or just shape accuracy?: Both matter — the game compares shapes at their actual canvas positions, so you need to remember roughly where the shape appeared.
What overlap score is considered excellent?: Above 80% overlap is excellent. 60–80% is solid. Below 50% means the shape category was remembered but detail was lost.

Built by

Ethan R. Caldwell

Game Developer · Wilmington, DE

Designed Can You Match This Shape? and 46 other browser puzzles. Game developer based in Wilmington, Delaware. Hardcore puzzle gamer at heart — obsessed with logic puzzles, sokoban-style mechanics, and physics-based brain teasers. Off the clock, unwinds with ARPGs, RPGs and JRPGs.

[email protected]