One suggestion: Adjust the game so that the player is only presented with countries that have populations within a certain distance of each other. Right now I'm getting a lot of "Marshall Islands vs Pakistan" type questions.
Might be fun to have a ranking for players as well to see how they did vs. everyone else. Like the old arcade video games did.
I am awful at this. I have always been surprised and excited by population numbers though so I had fun. Thanks!
Cool game. I also had a string of very easy questions early on that almost made me leave the page, so I think calibrating the difficulty is important. Maybe even start presenting harder or easier questions based on how the user has been performing.