In Civilization III, each civilization is categorized based on its strengths. There are six categories (Militaristic, Commercial , Expansionistic, Scientific, Religious, and Industrious), and each civ is attributed two categories. The Romans, for example, are a "Militaristic and Industrious" civ. Accordingly, they receive bonuses to some of their military and construction-oriented activities. These bonuses add another level of interesting choices to the game in that you will now want to carefully consider the strengths of a civ before you start playing. If you are an aggressive player, you might want to consider a "Militaristic" civ, whereas a player who chooses the route of diplomacy could be better served by a "Religious" or "Commercial" civ.
Each civ also has one "special unit" that only they can build, and depending on the tech tree, these units may become available at various stages of a game. This presents another interesting choice to consider: will you play as the Zulus, who get their Impi very quickly in the beginning of the game, or the Americans, whose F-15 will become available only in the modern era of the game?
Generally speaking, the "special" units have the same abilities as comparable units that all civs can build, with slightly upgraded attack, defense, or movement ratings. For example, the Babylonian special unit, the Bowman, has nearly the same combat ratings as the standard archer, but has an movement rate of 2 rather than the standard archer's movement of 1. Most special units also carry the same building costs in shields as their regular unit counterparts.
Another new concept we've introduced in Civilization III is the concept of a "golden age", which is meant to represent the period in history when your civilization is at its apex. During a "golden age", all worked tiles in your empire contribute one additional trade and shield per turn. Golden ages only occur once, last twenty game turns, and are triggered when any one of your civ-specific units wins its first combat against another civ. An interesting byproduct of the inclusion of these "civ-specific units" is that scenario and mod developers will now easily be able to create an entire roster of units that can only be built by certain Civilizations. This will give Civ III content creators a lot more freedom to create interesting scenarios and mods.
We are, of course, taking extra care to ensure that these bonuses and "special units" don't unbalance the game. Civ purists will be able to disable these new features and play with "Classic Civ" rules, but we think they add another level of challenge that most gamers will enjoy.