The pictures on this site and in the paper come from Wikimedia Commons, most of them its Featured Pictures. Each keeps its own licence, listed below with its author and source; on this site they are cut to a square and resized, and the model's reconstructions of them are derived works under the same licence.
The countries on the leaderboards of the arcade come from IP Geolocation by DB-IP, its free country database, under the Creative Commons Attribution 4.0 licence.