A free geography game: answer flag and capital quizzes to collect stamps from 54 countries. It plays like a travel stamp rally, so countries and their locations stick while you have fun.
Questions are in Japanese (interface in English). Your traveller rank climbs as you play, and the questions toughen up with you — great for geography starters and trivia lovers alike.
Answer the same question correctly twice and it graduates into a mastery card; the ranking counts how many cards you have collected. You can drill only the questions you got wrong, and every day you play adds a study stamp. No sign-up is required and your records stay on your own device. (The questions themselves are in Japanese.)