After you correctly guess the name of the country, traveling to it requires money. If you don’t have enough, it offers you a choice of either (1) picking a different country or (2) playing minigames to make more money. One of these is a math shooting game, another is “sokoban”, and the third is a slot machine.
If it started suddenly, then that’s a bug, because there are several menus the player has to go through before the minigame starts.