A free program for Android, by gedev.

This is a fun and addictive game that will help you learn about world countries and their flags, capitals, maps, continents, and currencies in the most fun way possible.

The game is a trivia app where you have to guess the country name or flag of the given country. You will always know the country name and flag of the given country, no matter how hard the question is. There are 14 single-player quiz types and 15 levels to finish. It gets harder progressively in this game.

You can also play this with friends with multiplayer mode.