Type 'easy' or 'hard' to begin the quiz. Easy is a 2-degree grid, hard is a 1-degree grid. Then, try to name the largest UK 1K+ 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 
Updated – as-of now Netherlands has 342 municipalities instead of 355 when I first made this quiz.
Maybe you could allow the Dutch names of Frisian municipalities.
If you have them let me know, I took what is on citypopulation.de
Wow, the municipalities of Friesland have really changed since when I knew them ten years ago.