new types of citizens to the game: Policemen (reduce corruption) and Civil Engineers (enhance building and wonder production). Culture is a feature that was not present in previous installments of the franchise. Each city has a cultural rating, which is the city's influence over local terrain. Essentially, the culture's outer edge, or "border", acts as the boundary of each civilization's empire. As the city's culture rating increases, so does its sphere of influence, bringing more territory under the player's control. Civilizations' borders may abut, resulting in their culture ratings vying for territory. If one player's culture rating is sufficiently higher than the other's, the former's borders will encroach into territory previously owned by the latter. Given enough time and cultural pressure, the latter player's city may even elect to join, or "flip to," the former's empire. Culture can thus serve as a means of peaceful conquest. Every civilization starts with certain special abilities, and they have a special "unique unit" that only they can build; these units usually have a historical basis (for example: the Japanese unique unit is the samurai, which replaces the standard knight, whereas the British unique unit is the Man-O-War, which replaces the standard frigate). Citizens have a nationality based upon the civilization under which they were "born." Citizens have a "memory" of their nationality and will consider themselves members of their previous civilization until they are assimilated into their new civilization. Combat is an important aspect of the game. Each combat unit begins as a "regular" unit with three hit points (although some units have additional hit points bonuses which affect their stats). If the unit loses all its hit points, it dies. Units can be promoted after successful combat missions and gain hit points. The highest rank a unit can attain is that of "elite" (which features five hit points), whereas the lowest is "conscript" (featuring two hit points; this rank is only given to newly drafted soldiers and barbarian units). Each unit has an attack and defense value to determine the winner of each battle. Additional defensive bonuses can be conferred by, e.g., certain terrain types, the unit's "Fortify" command, or defending across a river. Ultimately, a random number generator determines the outcome of each battle. When an elite unit wins a battle against an enemy unit, there is also a small chance that it will produce a Great Leader. A Great Leader