About Worml and its data

Worml is a free daily geography game about where animals live. This page explains where its data comes from, how it was processed, and — as importantly — what it is not.

What the game is

Each day every player is shown the same animal and has to work out which countries it is native to. There are no accounts, no sign-up and no tracking of individuals; progress and statistics live in your own browser and go no further.

Where the range data comes from

Ranges are compiled from IUCN Red List range descriptions and Wikipedia taxobox maps, covering 211 species across 151 countries. They are then simplified for playability, and every one of those simplifications loses information:

• Ranges are reduced to whole countries. Real distributions are continuous and pay no attention to borders. A species occupying two per cent of Russia is listed as occupying Russia.
• Wide-ranging species are truncated. Requiring every country a grey wolf lives in would make a chore of it, so the dataset carries a representative core and asks for a majority of that.
• Introduced and feral populations are excluded, because players reason about where an animal is from. The Nile perch is listed for the Nile, Chad and Niger basins but not Lake Victoria, where its introduction drove hundreds of cichlid species extinct.
• Historical range that has since been lost is excluded. These are present-day distributions.

How "closeness" is calculated

Every country is reduced to a single point: the centroid of its largest landmass. That detail matters more than it sounds — an area-weighted centroid of the United States lands in the Pacific Ocean, because Alaska and Hawaii drag it off the mainland. Taking the largest single landmass gives you the place people actually picture.

A guess is then scored against whichever country in the animal's range is nearest to it, by great-circle distance. That raw distance is normalised per animal: the scale runs from zero at the single worst guess available for that species, to one at a country in its range. Normalising per animal is what makes the colours informative — measured against a fixed global maximum instead, an animal living in Brazil would score almost every guess somewhere in the middle and the whole map would be one shade.

Maps and borders

Country outlines come from Natural Earth at 1:110m, which is public domain. At that resolution some small states are absent entirely, so a handful of genuinely island-endemic species cannot appear in the game at all. Territories that Natural Earth draws separately but ISO 3166 assigns no code — Somaliland, Northern Cyprus — are merged into the state that ISO recognises, so they colour in with their parent rather than leaving a hole. Borders follow that dataset and are not a political statement.

Photographs

Animal photographs come from Wikimedia Commons. Every one is credited to its photographer with its licence, on the results screen, in the full-size view and in the animal index. Most are Creative Commons Attribution or Attribution-ShareAlike, so that credit is a licence condition and not a courtesy.

A few species are so rarely photographed that no freely licensed image exists at all — the Ili pika is the clearest case, which is why Wikipedia illustrates its article with a distribution map. Rather than show a map, which would both fail to be the animal and give away the answer, those entries say plainly that no photograph is available.

Contact

Corrections to a range or a credit are welcome: hello@worml-game.com.