The series can be loosely described as ""SimCity" in past or imaginary civilizations with military and economic micromanagement". In the "City Building" series the player is put in charge of providing goods and services to the populace of their town, ensuring crime is low, and reducing the risk of disease, fire and building collapse. The player must also strike a balance between imports, exports and taxes to keep their town financially strong. The player is also responsible for defending their town against invasion by building a military.