A bit of a new wrinkle to the Name X In Y Minutes quiz to pass along: the minefield quiz given by Sporcle. Usually in a Name X In Y Minutes quiz, if you type in a wrong answer, all it costs you is a couple seconds. Here, one wrong answer is going to end the quiz.
That said, here's a quiz. Given 20 minutes, name the 100 most populous nations, without naming anything outside the top 100.
I managed 32 countries, including 21 of the top 25, before hitting #116.