The Conquerors expansion features many new differences. Farms can now be queued at mills to reduce micromanagement, villagers building a lumber or mining camp will automatically go to work collecting the respective resource once the camp is built. Additionally, infantry can garrison inside rams, making them more effective and easier to defend.
There are also several new units: the halberdier (upgraded pikeman), hussar (upgraded light cavalry), the petard (a kamikaze infantry with a moderate blast radius), and the unique units of the Spanish, Aztecs, Mayans, Huns, and Koreans.
New technologies have been introduced as well: bloodlines, caravan, herbal medicine, heresy, parthian tactics, theocracy, thumb ring, and the unique technologies: garland wars (Aztecs), atheism (Huns), shinkichon (Koreans) el dorado (Mayans), and supremacy (Spanish).
New multiplayer options are also introduced, such as King of the Hill and Defend the Wonder.
The most obvious change is the four new campaigns which are introduced: Attila the Hun, El Cid, Montezuma, and Battles of the Conquerors. The first three feature a six-level linear storyline, just like in the original Age of Kings, but the Battles of the Conquerors consists of eight readily available historic battles, which are disjointed and feature many various civilizations. As the other campaigns increase in difficulty with every level, the historic battles seem to get tougher chronologically, Tours (732 A.D.) being one of the easiest and Lepanto (1571 A.D.) being arguably the most difficult.