The three previous titles were mainly focused on fictitious islands in the Caribbean. Ubisoft has acquired the rights and will publish Anno 1404 world wide in March 2009. This franchise is much more well known in Europe than in the US, the original developer was in Germany.
Basically you colonize Islands and build cities while trying to build up a stable economy to support your military and diplomatic endeavors. In my opinion, the best of the franchise was 1503. Finally! another Anno game! For those of you who are not familiar with the franchise, it started with Anno 1602, followed up by Anno 1503 and Anno 1701.