How does the world map work?
After completion of the first city, New York, a world map will be unlocked.
All completed cities and those to come are displayed on this map and if you have completed the necessary levels and goals, you can scroll to the city you want to visit.
Tap on the city you want to play and enter at your leisure if you have unlocked this city before.
Cities can only be unlocked by completing all cities before it.