This is great - Few suggestions
(It's been a while for me, and I really like the new look and features! I did web-dev for a bit, and this is wonderful.)
So my friends and I really like this game, and we play in several "hardcore" modes. One of our modes is the following, which may be fun to include as an option:
(1) "Stand still mode": You're dropped somewhere, and you're not allowed to move except by rotating the view. (This is different than the related "5 seconds only mode" in that in 'stand still mode', you can think for as long as you want, and try to be a detective [which is definitely part of the fun!].)
(2) Users pick how their score is assessed. So casual players can pick an option that gives points more generously. But hardcore players can pick options that are stricter. And you could add options where you're penalized for extra time or for taking extra steps.
(3) This is obviously hard to code, and you probably already thought of it, but the score system shouldn't be based just on distance. If the correct answer is Australia, then a guess of South Africa should get much more points than a guess of Japan. [Obviously hard to even say what this would mean. Mathematically speaking, you would just be replacing the usual distance on the globe with a different metric. But then you have to assign a number that says "how similar is this city in Ukraine to that city in Russia?". A true headache.]
(4) You could have a 'cities only' mode. This would not be super hard. You just need to make sure that when the start location is picked, it's in a sufficiently populated area. You could do this by either reselecting the position server-side if it's not sufficiently populated or by doing some pre-processing to get a big pool of cities. [Such a database must exist.]
(5) Have a "hint" option that points towards some nearby town(s).
(6) Having a scoring system that doesn't emphasize location as much in the folowing way: Your guess is perhaps a combination of a location as well as a sort of description of the place. For example, have options for the user to say what language the people speak, which oblast of Russia you're in [hint: look for unblurred liscence plates], et cetera. That way they can get points for what they knew.
(7) Perhaps allow the user to make two guesses.
In all, this is great. :-)