Concentrating on the late medieval period, Age of Chivalry: Hegemony replaces or significantly alters each of the civilizations in the original game, while adding a number of new ones, allowing the player to control Central and Western European states. Many new units and technologies have been added and gameplay dynamics have been changed considerably in this complete overhaul of Age of Empires II.
The next patch for Age of Chivalry will be released within a few days, but until then, here's a screenshot of a town in Guelders, featuring (among others) new graphics for the church and other buildings.