Type 'easy' or 'hard' to begin the quiz. Easy is a 15-degree grid, hard is a 10-degree grid. The grid will be randomly placed on the map. Then, try to name the largest 50K+ cities in each square IN ORDER. 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).
The squares will start with '0/5' (or maybe fewer cities if less exist in that square). Click on a square and enter the largest city in that square not yet answered (so, the largest city if you have yet to answer a city in that square). You will then have '1/5' and need to click on that square to name the 2nd largest city, and so on until you complete all the cities up to 5 (or less if less exist). If you name an incorrect city in a square it becomes 'locked' and turns red and you can no longer accumulate cities in that square.
You receive 1 point for the largest city in a square, 2 for the 2nd largest, and so on.
At the end of the quiz the largest remaining city you haven't named will be shown in each square.
Quiz Takers 
Each answer should accept any large city (say, the 3 or 4 largest, for example) within the agglomeration. The instructions don’t say only the largest city is accepted.
*SPOILER*
For example, the #1 answer is “Guangzhou”, which is really just one of the cities in the Guangdong-HongKong-Macau agglomeration, which also includes Shenzhen, Dongguan, and Foshan (each of which has a population 9,000,000). I entered a few of these cities unsuccessfully. Shenzhen even has a larger population than Guangzhou, according to Wikipedia, but it’s not accepted.
I’ve heard it called the Pearl River Agglomeration, but that doesn’t exactly flow off the tongue. But I do often see it referred to as the Guangzhou urban agglomeration, so this wasn’t just something he made up for the quiz. I think Guangzhou was at one point the larges (or oldest?) of the cities there, probably where that came from.
i guessed Chicago, its 51st LOL