First enter a difficulty level by typing ‘beg’, ‘int’, ‘adv’ or ‘exp’. Beginner is 500km, intermediate is 250km, advanced is 150km and expert is 100km. Every 1M+ pop agglomeration within that radius will fill in. I tried to include a few cities that may not be the main city of the agglo, but try to name the agglo’s largest/main city.
Enter level to begin ('beg', 'int', 'adv', or 'exp').