@Draconophile ... that's why I have choosen to take a non spherical map. Of course it might happen that a large distance is not 100% correct, though I really tried to meassure all possible positions. Calculation the sphere distance is far from my knowledge actually.
@iownyoualot ... that's simply not true! Please check again. Like I said earlier I have seen plenty of games like this .. The first one was a console game I played in 2004. One thing that is quite similair to the facebook app is the popup window. The rest is nothing new.
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