"Not unlike the earlier games in the series, Emperor focuses on the building and development of a city in ancient times, this time Ancient China, from the Xia Dynasty (2033 BC) to the Song-Jin Dynasties (1234 AD).
The most basic task in each mission is to maintain the city. This involves keeping the populace well-fed, healthy, and safe from hazards. If food and basic goods and services are provided in abundance, the city will eventually improve. Beyond this, the player must manage trade and taxes in order to fund further development and expansion.
In the meantime, the player may elect to make offerings to the ancestral heroes. Principally, offerings are made to appease the heroes and prevent them from becoming angry and inflicting disasters upon the city. But heroes can also be made very happy, which can prompt them to visit the city and confer benefits to it.
Beyond the city itself, the player must pay heed to rivals and enemies. Troops and guards are necessary to protect the city from military invasions and subterfuge. The player can build defensive walls and man them with archers for improved defense.
Eventually, the player may be required to build monuments, which are costly both in time and materials, giving enemies an opportunity to take advantage of possible weaknesses. As such, building a monument generally requires that the city first establish a strong economy and military.
Source: Wikipedia, "Emperor:_Rise_of_the_Middle_Kingdom," available under the CC-BY-SA License.