GeoChallenge includes a handy searchable reference list of all countries and their capitals. Simply tap the book icon at the top left of the main screen. From here you can use scroll down the list, or use the search bar to quickly find a country or capital. Tapping a country will show you more information, including its flag, capital, and a zoomable map of its location.
This reference is somewhat basic for now, but we hope to expand on the information contained here in future updates, as well as include information for states/regions in the countries we have challenge quizzes for.