Civilization is a turn-based single-player strategy game. The player takes on the role of the ruler of a civilization, starting with one (or occasionally two) settler units, and attempts to build an empire in competition with two to seven other civilizations. The game requires a fair amount of micromanagement (although less than other simulation games). Along with the larger tasks of exploration, warfare and diplomacy, the player has to make decisions about where to build new cities, which improvements or units to build in each city, which advances in knowledge should be sought (and at what rate), and how to transform the land surrounding the cities for maximum benefit. From time to time the player's towns may be harassed by barbarians, units with no specific nationality and no named leader. These threats only come from huts, unclaimed land or sea, so that over time and turns of exploration, there are fewer and fewer places from which barbarians will emanate. Before the game begins, the player chooses which historical or current civilization to play. In contrast to later games in the Civilization series, this is largely a cosmetic choice, affecting titles, city names, musical heralds, and color. The choice does affect their starting position on the "Play on Earth" map, and thus different resources in one's initial cities, but has no effect on starting position when starting a random world game or a customized world game. The player's choice of civilization also prevents the computer from being able to play as that civilization or the other civilization of the same color, and since computer-controlled opponents display certain traits of their civilizations this affects gameplay as well. The Aztecs are both fiercely expansionist and generally extremely wealthy, for example. Other civilizations include the Americans, the Mongols, and Romans. Each civilization is led by a famous historical figure, such as Mahatma Gandhi for India. The scope of Civilization is larger than most other games. The game begins in 4000 BC, before the Bronze Age, and can last through to AD 2100 (on the easiest setting) with Space Age and "future technologies". At the start of the game there are no cities anywhere in the world: the player controls one or two settler units, which can be used to found new cities in appropriate sites (and those cities may build other settler units, which can go out and found new cities, thus expanding the empire). Settlers can also alter terrain, build improvements such as mines and irrigation, build roads to connect cities, and later in the game they can construct railroads which offer unlimited movement. As time advances, new technologies are developed; these technologies are the primary way in which the game changes and grows. At the start, players choose from advances such as pottery, the wheel, and the alphabet to, near the end of the game, nuclear fission and spaceflight. Players can gain a large advantage if their civilization is