Type 'easy' or 'hard' to begin the quiz. Easy is a 5-degree grid, hard is a 2.5-degree grid. Then, try to name the LARGEST European 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 
Helgoland, Koserow and Selfkant aren‘t cities, why are they included on this quiz? Or does it count all municipalities, regardless of their official classification?
they actually are counted as settlements/communes by the German census
It´s usually spelled Heligoland, not Helgoland tho
i’ll change to accept both.
That’s the English spelling, in German it’s Helgoland
On int difficulty, in the square in the northeast around szczecin/stettin, the largest german city is definitely schwedt/oder (33.524 inh.), but it doesn’t accept this nor any other significant town in the region as solution
Found the problem: some towns with “/” in their name are only accepted without it, so “schwedtoder” instead of “schwedt/oder”