First choose a level by typing ‘beg’, ‘int’, ‘adv’ or ‘exp’ – beginner is 2,500,000, intermediate is 1,000,000, advanced is 250,000 and expert 100,000. Then, begin naming cities. All cities of at least 1K+ population starting with the city you chose and moving outward will begin filling in until you’ve hit a total population equal to or greater than your chosen level’s threshold. For example, if you choose ‘int’ – the threshold is 1 million. If you choose ‘glasgow’, then Glasgow will fill in and because its population is under 1 million, successive cities moving outward from Glasgow will fill in until the total population reaches at least 1 million. If you chose London, only London would fill in as its population already meets your threshold.
Enter level to begin ('beg', 'int', 'adv', or 'exp').