"World Flags" an educational game software which can recite the whole world flags throughout the game. Even if the flag as I know, do not worry. Flags of the countries did not know step-by-step through the stages can also be naturally memorize.
※ This game is open source. Anyone who are interested in game development You can get the source code via the following url for this game. http://github.com/sunduk/WorldFlagGames