It's interesting to see how some of the cities' metro nets have changed over the years. For instance, when I was in Singapore in 1998, there were just two lines, the yellow and the green one. By now, it seems to have turned into quite a web. And something similar happened to the Chinese ones.
Great Quiz, waiting for a part 2. Other than that I guess these maps are old now, becuz I know Delhi Metro has expanded even more with 2 new lines.....