Creative Assembly takes real time strategy to the next level.
The diversity of civilizations and their respective units, each with it's own strengths and weaknesses, means the game never gets old. Players will want to conquer the world time and time again, as different factions from the four corners of the globe.
If there is a weakness, it lies in the AI, which can be a little uneven in places. Diplomacy, for example, often borders on lunacy. Why on earth does an allied faction, significantly weakened by wars with other kingdoms, arbitrarily decide to stab me in the back and start a war with me which they can't possibly win? Still, even this wonkiness can add some amusing-if-unrealistic aspects to the game, and players will often find themselves laughing out loud at some of the ludicrous proposals made by other factions.
Bottom line, if you're a fan of real-time strategy with epic battles, then Rome: Total War needs to be added to your collection.