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 
need to allow full screen mode and also make the correct marker a different color (currently both are green if you guess close)
Kinda hard to click on phones and tablets but it’s like this everywhere so it’s not that bad
How does the quizz start ?
was a bug – fixed.
why for 0 km you still get 99 and not 100
You can always use the zoom function though admittedly it will make you lose some time zooming in/out and moving the map around. Previous locator quizzes were not timed so it adds an extra challenge.
A little hard to click precisely when places are so close (especially around Paris), but nice quiz.