First choose any Europe 10K+ pop city by entering it and choosing it in the drop-down box. Then, name any Europe 10K+ city in each 100 km circle/ring as the rings expand outward from your city of choice, trying to name SECOND LARGEST city in each circle. The first circle will include your city of choice as a possible answer.
PLEASE NOTE - You must type a '.' (period) after each city to submit it to prevent answering another city with a name you would be have to type to get your answer. If multiple cities have the name you submitted, only the largest one will be counted.
You accumulate points based on the population of the city you named in relation to the second largest city in the circle. A smaller city’s point total will be the ratio of its population to the largest, so if you name a city of 75K people and the largest city has 100K, you get 75 points. Naming the largest city will get you points based on the ratio of the 2nd largest city's population to the largest city's.
When you run out of time or end the quiz, you will see the current ring’s 2nd largest city at right (under ‘Answer Stats’ by your coordinates).
For example, if you choose ‘Paris’ – you will be shown a circle of radius 100 km centered at Paris. Naming any city in this circle (including Paris) will cause another ‘ring’ of radius 100 km to appear outside that circle, however - you will want to try naming the SECOND LARGEST city you can to get more points. After completing that circle, you now need to name any 10K+ Europe city in the new ring (but not within any previous circles/rings), again trying to name the 2nd largest city. If there are not two cities within the next ring of that distance, the ring will keep expanding by that distance until two cities fall within it.
Quiz Takers 
Was muss man denn eingeben, damit die Stadt Offenbach grün wird? “Offenbach” jedenfalls nicht. Da wird nur der Kreis grün.
Sie müssen “Offenbach am Main” schreiben.
I had 259, but the score was not saved. 🙁
I like the quiz (but I’m also from Germany, so it’s not so hard for me), but I’m not so happy with the update.
1) in the previous version the german ä,ö and ü worked alongside a, o and u, now they don’t anymore.
2) the abbreviations are kind of odd. For example I didn’t get ‘Neumarkt i.d. OPf.’ because I couldn’t guess what kind of abbreviation you used. The correct name would be: ‘Neumarkt in der Oberpfalz’, but that does not work. ‘Neumarkt i.d. Oberpfalz’ also didn’t work. And there are several other examples where either the abbreviation worked, but not the whole title, or the other way around, and no abbreviation would work. That could definitly work better.
3) You don’t need the exact name of the district any more, which you needed in former versions. I’m not so happy with this, because if you type in ‘rhein’, you will get six or seven districts, which all starts with ‘rhein’. That should not really be the case. Also the difference between a district and a ‘free city’, which have often slightly different names, get lost.
4) if the word ‘kreis’ (german for district) is part of the name without a space between, you have to type it, but not if its an extra word (saalekreis <-> rhein sieg kreis), which is not so konvenient. That was also the case in former versions, but not typing the word ‘kreis’ if its at the end would definitly be more konvenient.
I’m using a new dataset now and the names have changed in it, ill try to fix the names so they are closer to the old way.
Rer ich weis gar nix