Type 'easy' or 'hard' to begin the quiz. Easy is a 15-degree grid, hard is a 10-degree grid. Then, try to name the SECOND LARGEST city in each grid square. To name a city, you must first click on the grid square to make it have a GREEN border. Then, type in the city answer for that square followed by a '.' (a period). You are given a score from 0 to 100 based on your answer's population compared to the 2nd largest city accepted in that square (100 being you named the 2nd largest city). If you guess the largest city it will be based on the ratio of the 2nd largest city's population to the largest.
At the end of the quiz the 2nd largest city will show in each unanswered square, and for those answered the 2nd largest city will be listed next to your score if you didn't answer it.
Quiz Takers 
I don’t think this source is trustworthy. The entire REGION that Massawa is in has under 1m people by every source I’m able to find (I’ve seen estimates as low as 400k and as high as 900k).
how massawa is bigger than asmara and fomboni is bigger than moroni?
I believe the answer for Germany is incorrect – Berlin as a city has a higher population than the number next to the listed answer
Per the source it’s the largest. Urban areas can be defined different ways depending on the source.
Sorry, but it’s wrong. Dortmund is part of the Ruhr area which is not called dortmund. Ruhr area has much more people though. Even Berlin has more than 3.4 mil
I agree. It should either be “Rhein-Ruhr” or “Berlin”. No German or European would ever call the Ruhrgebiet, Dortmund. Dortmund is just one of the many towns making up the area.
The answers for Comoros and Eritrea seem to be incorrect.
per the source those are the largest by the source’s definition.