Draw a Gear From Memory

A cog with eight teeth, on screen for a couple of seconds, then gone. You draw it back from memory onto an empty canvas, and your attempt is scored against the target and laid over it afterwards, so you can see which teeth landed and which ones you invented.

The trap is that a gear is remembered as an idea, not as a count. You remember “a gear”, and then you draw however many teeth feel right - which is easily not eight. Even with the count correct, the spacing is what slips: teeth bunch on one side and the gaps stretch on the other, because the eye keeps the shape and drops the rhythm.

The target is one closed outline of 32 corners. Each of the eight teeth is a short trapezoid - 18° wide where it joins the ring and a flat 10.8° across its top - and they are spaced 45° apart, so each gap is wider than the tooth beside it. The gear is 72% of the canvas across, and the teeth stand only about 10% of the canvas tall.

This is a practice round: played and scored for real, and it changes nothing in your game - no coins, no best score, no unlocks - so you can take it as often as you like, whether or not you have reached the gear in the Shape Challenge.

A gear is mostly sides and gaps

The gear is one closed line, and the scorer spreads its 128 comparison points along it by length. The sixteen sides of the teeth hold 52% of them (66 points) and the eight gaps between teeth 31%. The eight flat tops - the part that looks most like a tooth - hold only 17%.

The scorer tries every starting point in both directions, so where you begin and which way you go round never matter. What matters is that the teeth land where the target's do around the ring: shape match is held to the worst-matching tenth of the outline, and a gear with the wrong number of teeth is wrong all the way round.

Each part's share of the line, and of the scorer's comparison points
Part	Share of the line	Comparison points
Tooth tips - the eight flat tops	17%	22
Tooth sides - sixteen flanks	52%	66
Gaps between teeth - eight floors	31%	40

Tooth count, spacing and rounding

The same hand, with nothing wrong, scores 91. Draw six teeth instead of eight - a clean, even gear, just the wrong one - and it scores 71, with coverage down to 89: 20 points for getting the count wrong.

Keep eight teeth but let each sit up to 9° from its place - a fifth of the 45° between teeth, so they bunch on one side and spread on the other - and it scores 79. Round the tops and shoulders into bumps and it barely matters: 88. The scorer is looking for the count and the spacing, not for sharp corners.

The eight-tooth gear target in grey with a freehand gear drawn over it in blue that has only six teeth, spaced further apart — Six teeth instead of eight, over the target. Scored by the game's own scorer: 71 / 100.

Scored by the game's own scorer, out of 100
Attempt	Total	Shape	Coverage	Smoothness	Scale
The same hand, no mistake	91	89	99	68	99
Six teeth instead of eight	71	61	89	76	98
Teeth bunched on one side, gaps stretched on the other	79	73	99	68	100
Tooth tips and shoulders rounded off	88	87	97	66	96

Three drills for the gear

Teeth at the compass points. Eight teeth means one at the top, bottom, left and right, and one in each diagonal between them. Mark those eight places in your head before you start and aim a tooth at each.
Gaps wider than teeth. At the ring, each tooth is 18° wide and each gap 27° - a gap is half as wide again as a tooth. Draw the gaps wider than the teeth.
Short, tapering teeth. The teeth stand only about 10% of the canvas tall against a gear 72% across, and their tops are narrower than their roots (10.8° against 18°). Draw them as short trapezoids, not as long spikes.

Questions people ask

What happens after the shape disappears?: You draw on a blank canvas with no guide underneath, in one attempt. The outline comes back afterwards, laid over your drawing so you can see the difference.
How is my score worked out?: Shape match, coverage, smoothness and scale, combined into one score shown with a star rating and a tip. Shape match counts for the most, at 70%.
Can I play with other people?: Two ways. 2 Players passes one device back and forth, alternating who draws first each round. Multiplayer opens a live room for 2–8 players over 5, 10 or 15 rounds, joined with a six-character code.
How many shapes are there?: 276 shapes across 12 categories, from geometry and letters to animals, food and fantasy.

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