This era add-on was made to give players more advancement options, with a number of units added to each of the default factions. All of the new units were made with a consistent art style to ensure that they blend in with the existing units of the default factions. Additionally, 2 new factions were also added, the Empire and Zombai. The Zombai faction was made to be used for Zombie AI survival mode on any map you wish, this faction will progressively unlock stronger units as turns passes. This add-on also includes a dismount mod, ensure it is enabled to mount and dismount your cavalry units.
Visit the official forum thread for more information about the Era, the new units and new features.