Each round shows part of the world map, and one country on it is wrong.
It may have been made bigger or smaller, turned, flipped, moved to the wrong place, merged with a neighbour, or it is missing and a neighbour has its land.
The question tells you which kind it is.
The map is wide. Zoom in with the buttons, two fingers or Ctrl and the wheel to look closely.
Five rounds make a game. The difficulty sets how well known the countries are and how much of the map changes.