Type 'easy' or 'hard' to begin the quiz. Easy is a 15-degree grid, hard is a 10-degree grid. A random grid will be placed on the map. Then, try to name the THIRD LARGEST World 50K+ 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 3nd largest city accepted in that square (100 being you named the 3nd largest city). If you guess the largest city it will be based on the ratio of the 3nd largest city's population to the largest.
At the end of the quiz the 3nd largest city will show in each unanswered square, and for those answered the 3nd largest city will be listed next to your score if you didn't answer it.
Quiz Takers 
Curious why the second Indian city is Mira Bhayandar and not Thane?
Per typing in Thane on Google Maps, it looks like the eastern part of the city is not on the island.
1) Of the five boroughs of New York City, only The Bronx is not entirely located on islands. I say it should count.
2) While the majority of Hong Kong’s residents do live on the mainland, if you only counted the island population of Hong Kong, it would still make the top 40 overall.
3) Same goes for Xiamen (Huli + Siming = 2.1 million).
4) I don’t believe any part of Zhongshan is on an island.
I want to include cities entirely on islands. Also it appears Zhongshan is entirely on a river island (Zhongshan island).
Geoje(South Korea) is also a city located on an island.
will add, thanks.
Would you consider doing one that’s largest cities above a certain altitude?
it’s tough because largest cities can cover a large span of altitude
Venice is a curious case… the city center is definitely on an island but the majority of the population of the Venice commune is found mainland. A little known fact I think.
Yes, I guess it’s a good criteria.