Unlike past Total War games, Rome will initially allow the player to be only Roman. Fortunately, there are three different Roman factions to choose from - the Julii who are aimed at Gaul and Germania to the Northwest and North, the Brutii who face the East with Dalmatia and Greece beyond, and the Scipii who face South across the Mediterranean. There is a fourth Roman faction, the Senate, which plays a guidance role. It gives the player tasks that he may choose to complete, it can subsidize him and, if he gets too powerful, it may turn against him.
One of the weak points of both Shogun and Medieval was that the late game became both dull (since the challenge was gone) and tedious (because you ended up managing so many provinces). With Rome, this changes. As with its historical source, Rome around 270BC, at the start of the game, was a budding power but it was regional, contained in Italy. Roman forces were not necessarily dominant at this time, it was only later that the mighty legions sprang forth. However, as with historical Rome, the legion and other tools of war will appear and the Romans will almost assuredly secure primacy in the Mediterranean basin. The goal for the player is to secure that primacy for himself in Rome itself.
If he plays well, the player will amass enough power for his faction to proclaim himself the Emperor. Or rather, the player proclaims the leader of his faction as the Emperor. As with Medieval and Shogun, the player leads a family. This time around, that aspect is even more important since the best, and most loyal, generals are those related to the faction leader. Fortunately, in both virtual and ancient Rome, adoption is a common and accepted practice. Thanks to the declaration of Empire, the endgame will be an intense Roman civil war, ending only with the capture of Rome. This should solve the late-game doldrums problems. Other factions, when unlocked, will have different goals - to control a certain number of provinces, for example.
Along with the new engine there will be of course a completely redesigned interface. No longer will the player spend 5 minutes memorizing what was built where and what faction assassinated what general and which priest was doing which task, while clicking off a seemingly endless number of popups. Instead, the interface will be streamlined, providing a summarized lists of completed tasks.
Creative Assembly has promised a very detailed and important diplomacy system. Players will be able to demand or offer alliances, peace, bribes, and land. They'll be able to ask their neighbours to wage war against a common enemy, or to demand them to stop attacks.
The AI will be able to control most aspects of the game, so if a player would rather not handle the building of armies or cities for example, he can ignore that and just play the battles. Or, if he'd rather manage an empire rather than fight those battles, that is possible as well.