From Totalwar.com game description of Shogun 2:

"A complete single and multiplayer offering:

Play through the Main Campaign in single player or invite a friend online to play competitively or cooperatively in Campaign Multiplayer mode. Join 8-player multiplayer battles with your own upgradable avatar and climb the online Leaderboard to show the world who reigns supreme. Also including exciting new modes of team play for clans, a first in the Total War series."