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 LARGEST city in each grid square which fits the category label for each 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 largest city accepted in that square (100 being you named the largest city).
LETTER: means the city starts with that letter.
NUMBER RANGE: (such as 2-5, 10+) means the city contains that many letters (excluding spaces and special characters).
POPULATION RANGE: (such as 50-100K) means the city has that range for its population.
2+ WORDS means the city name has 2 or more words (words denoted by a space or hyphen).
At the end of the quiz the largest population missed answer will show in each unanswered square, and for those answered the largest city will be listed if you didn't answer it.
Quiz Takers 
great quiz! Really enjoyed not having to stress about time too!
Hey, its a little bit weird, that cologne gets accepted for ruhr, because Cologne is definitly not part of the Ruhr-area, which, more or less 50 km north of Cologne, ranges from west (duisburg) till east (Dortmund) with relatively little north-south-extent, containing as biggest cities Dortmund, Essen, Duisburg and Bochum (amongst several others over 100.000 population).
The source site (citypopulation.de) changed to include Cologne as part of the Ruhr agglo, and not its own separate one.
Hey Darren, mind adding the source for this one? Doesn’t seem to be Demographia’s World Urban Areas list this time.
I think I misspelled your name lol, forgive me.
citypopulation.de
Thanks!! Do you still use the Demographia list in any of the quizzes? Or am I just confused, ha?
citypopulation.de is my only source for population numbers