Reading the quiz map
Every map is a compromise between a round Earth and a flat screen. Knowing which compromise this one makes helps you read it faster.
An equal-area projection
The map uses the Equal Earth projection. Its main property is that areas are true to scale: a country that covers twice as much land as another also covers twice as much of the map. On the familiar Mercator maps, countries near the poles look far too large; Greenland seems as big as Africa although Africa is roughly fourteen times larger.
The price is some distortion of shape towards the edges of the map, where countries look slightly squeezed. For a quiz about where countries are and how large they are, honest areas matter more.
Meridians and parallels
The faint lines are meridians and parallels. On the country pages they are drawn every five or ten degrees. They are useful anchors: the equator runs through Ecuador, Kenya and Indonesia, the prime meridian through the United Kingdom, France, Spain and Ghana.
Borders as they are on the ground
Outlines come from Natural Earth, a public-domain map collection, at the scale 1:110 million. It shows de facto boundaries, the situation on the ground, without taking sides. Disputed land and territories without independence get a plain grey fill, no label and no questions.
At this scale lakes and very small islands are not drawn, and coastlines are simplified. That keeps the map light and quick on a phone, and it is detailed enough to recognise every country.
Dots for the smallest states
Twenty-nine states are too small for the outline map, from Vatican City to the island states of the Pacific. They appear as round markers that you can tap. On a phone at the world view, even some outlined countries such as Belgium or Slovenia are small, so zoom in before you answer.
Moving around
Drag to pan, pinch or use the mouse wheel to zoom, and use the three buttons in the corner to zoom in, zoom out or show the whole region again. A tap only counts when the finger does not move, so exploring never answers by accident.
Each region has its own view. The continents are zoomed in; Oceania is centred on the Pacific so that the islands on both sides of the date line stay together.