2. Rome: Total War
One of the most impressive aspects of Rome: Total War is that it's essential two completely separate games brought together for a single experience. As leader of the sprawling empire, much time will be spent shifting battalions, improving infrastructure, and negotiating peace treaties with your neighbors--all of the big picture concerns of a well-fueled army.
As a commander, however, your place is with your men on the battlefield. Rome: Total War's centerpiece is the action itself, a superb recreation of tactical combat common within the time. With thousands of soldiers clashing on each side, positioning, terrain, unit types, experience, and morale are all considerations that a successful general must take into account to achieve victory. Bring these two halves together, and you've got the most robust military campaign simulator around.