Another real time strategy game released in the early 90's for the PC Amiga and Sega. I still have my old copy laying around for my Sega and Theme Park as well. This is one of the games I played most as a child until things like Command and Conquer and X-Com were released.
The game begins in Ancient Rome in the year 275 BC, placing the player in the sandals of a centurion in the Roman army, at first leading a single legion. The player's ultimate goal is to become a Caesar through a mix of successful military conquests and internal politics.
The bulk of the game involve turn-based strategic planning and management on the world map and the real-time battles (with on-demand pauses to give orders to formations) against various enemies of the Roman Empire, such as the Celts, Carthaginians and Parthians. Centurion also featured other "side-show" activities, such as chariot racing in the Circus Maximus, and naval battles. There is also some diplomacy.
So yea you start off with just a single Legion and General with only the home province and it is your duty to conquer the known world and become Caesar. Due to the small amount of areas to conquer this would seem a trivial task except for the fact that from time to time enemy armies will appear on the map and attempt to destroy all your hard work. If they are able to take a province you must re-conquer it and you must deal with the marauding army as well which means two battles in a row. This can be really frustrating with places such as Persia(IIRC) as they have an entire army of nothing but cavalry.