Where the outlines come from, and why the geography ones are different
An outline in this game does two jobs. It has to be recognisable at a glance, and it has to be honest about proportion, because the shape is what you are judging against. Those two jobs are in tension more often than you would think.
Two kinds of shape
The 585 outlines behind this game fall into two groups that are not really the same kind of object.
The 118 geographic shapes are derived from open mapping data. A coastline in that data is a sequence of coordinates measured from the real world, and the outline you drag on screen is that sequence projected and scaled. Its proportions are not an artistic decision.
Everything else is a drawn shape: a traced profile of an animal, a building, a ship or a character. Those carry a real measurement attached to them, but the outline itself is a rendering, and a rendering involves choices.
Why the distinction matters for the game
Because you are judging the shape, not the number. If the outline of a giraffe is drawn with the neck slightly too long, the animal's stated height of 5.3 m is still correct and your visual estimate is still being pulled in a direction the measurement does not account for.
For geographic outlines that failure mode does not exist. Texas at 1,244.8 km east to west against the United Kingdom at 1,220.5 km north to south is a comparison where both outlines came from surveyed coordinates and the ratio of 1.02 is trustworthy in the shape as well as in the figure.
The practical consequence: the Geography game is the one where a careful player can reason from the drawing itself. In the other two, the drawing tells you what the thing is and the measurement tells you how big it is, and those are separate channels.
The pose problem
A drawn animal has to be in some pose, and the pose interacts with the measurement in ways that need deciding.
A grizzly bear measured at 2.5 m is upright on its hind legs, so the outline has to be an upright bear. Drawing a bear on all fours and attaching the upright figure would be a straightforward contradiction between the picture and the number.
A leatherback turtle at 2.35 m is drawn in a swimming pose, flippers extended, because that is the posture the measurement convention assumes. Against a London black cab at 4.6 m the ratio is 1.96, and both figures are lengths of objects in their normal configuration.
Steelix is the awkward case. The stated height of 4.45 m is for a coiled pose, and the same creature uncoiled runs more than twice as long. Both numbers describe it. The outline had to pick one, and the figure had to match the outline rather than the other way round.
When one object needs two outlines
Occasionally a single thing genuinely needs two entries, because it has two measurements depending on the view.
The Airbus A380 is the clearest. From the side it is 72.72 m long. From above it is the same 72.72 m, drawn as a very different outline: the wings spread to 79.75 m on either side of a figure that does not count them. The plan view against a 341 m rotor diameter puts a fuselage length beside a span, and the page is explicit that the two do not describe the same kind of reach.
The alternative would have been to give the aircraft one outline and two figures, which breaks the rule that every object has exactly one measurement and one axis. Keeping that rule intact is worth the duplication.
How much detail survives
Geographic outlines carry a great deal of data, because a coastline never stops having detail: zoom in far enough and there is always another bay. The full outline for a large country runs to tens of thousands of coordinates.
Drawing all of them would make a page heavy for no visible benefit, so the outlines are reduced with a tolerance tied to the size the shape will be drawn at. Points are removed only where their removal moves the line by less than a fraction of a pixel. The result is visually identical and a fraction of the weight.
That reduction is done per drawing rather than once in the data, which means the game itself still has the full outline available. It is only the static comparison pages, where the display size is known in advance, that use the reduced version.
Recognisable against honest
This is the tension that never fully resolves. A silhouette that exaggerates a distinctive feature is identified faster. A silhouette that keeps true proportions is a better thing to judge size against.
The catalogue goes with proportion, and the cost shows up in a handful of shapes that are genuinely hard to name out of context. A whale shark and a basking shark have similar profiles. Several of the large land mammals, reduced to a filled outline, need the label.
That is the right trade for a game about size. It would be the wrong trade for an illustration, which is why the same shapes would not be a good choice for a poster.
Where the provenance lives
All 585 outlines are listed on the sources page, with the provenance and the rights basis recorded for each one, and the list can be searched by name. The geographic shapes name the mapping datasets they come from.
That page is not decoration. A measurement without a source cannot be checked, and an outline without a provenance cannot be either. Publishing both is what makes it possible for someone to disagree with a specific figure rather than with the whole exercise, and a disagreement that specific is the most useful thing a reader can send.