I had tried this back when it first went free and now wanna tout it here; Forgetful Dictator is the solidest piece of edutainment I've ever seen about country & capital learning/memorization. It's funny, smartly designed, and truly rewarding by teaching players more about all (known) human societies across our planet. I think everyone should give it a try, especially since it has many difficulty levels, from complete beginners to memory masters.