Real time games with fairly good AI for solitary play. A good enemy commander and decent troops will kick your butt when you don't expect it.
You can also play multiple players on line.
TW Medieval is best with three historical periods and many specialized units for the contenders, some not available to other factions. It has 12 playable factions. I don't have TW Medieval II, yet.
TW Shogun, Warlord Edition is more intricate and far better than TW Shogun.
There are lots of opportunities to learn military history with several websites and clubs devoted to the games.
I now understand the Byzantine Empire history and the tragedy of its destruction as never before.
I now have some knowledge of Japanese regions and the family names of the warlords during the Japanese medieval period. Japanese movies such as "Heaven and Earth" are fleshed out and more meaningful for me. The same characters are in the games.
You can also check out the problems of the three different Moslem factions.
http://www.totalwar.com/ Total War company website
http://www.totalwar.org/ Fan site
http://pc.ign.com/objects/800/800327.html Another site, check them all out!
I recommend them to ACW wargamers.
BG Ross McDaniel