Moderators of the wildly popular VORPG, Polyworld, had no idea that one of their most famous cites Edotown had been stolen and for quite some time. No wonder there were so many complaints and bug reports coming in.
Surnames: The Chinese were among the very first cultures to adopt the use of hereditary surnames (around 2800 BC). But the custom didn't quite catch on in Europe - at least not until the Venetian aristocracy made it popular sometime between the 10th and 11th centuries AD. What culture made it popular in your setting and why?