The titles are probably self-explanatory but Medieval II: Total War is set between 1080 and 1530, focusing on medieval warfare, religion, and politics, and notable events include the colonization of the Americas. Likewise, Medieval II: Total War Kingdoms adds four campaigns revolving around the discovery of the Americas, 13th century Britain, and more.
Rome: Total War - Gold is set in the Roman Republic and includes the first expansion pack, Barbarian Invasion. Rome: Total War - Alexander is the second expansion, and puts players behind the sword of Alexander the Great during some of his most famous battles and impressive victories, such as Battle of Issus and Battle of Gaugamela.
Empire: Total War is largely set in the 18th century, with battles on both land and sea, allowing players to engage in real-time 3D naval combat. Events include the French Revolution, Age of Enlightenment, and the Industrial Revolution. There are five DLC packs, but none of them appear to be included in the base price.
All of the games mentioned have a metascore of 85 or better, with the exception of Rome: Total War - Alexander. It's also worth noting that the latest installment in the series, Napoleon: Total War is coming later this month, and happened to make our list of 2010's most anticipated PC games. The sale ends next Monday, February 15.