I think the game could have been made infinitely better by having different missions that reflect each forces fighting style and using the face buttons not the thumbsticks for attacking and defending.
For instance Vikings should have berserkers who fly into unstoppable rages, while samurai fight using kendo, bojutsu, and other Japanese martial arts weapons and styles in accordance with their bushido code which was all about Honor with missions that reflect this while Ninjas missions and fighting style would be entirely stealth based espionage missions and could see Chinese martial arts styles like various forms of Kung fu and weapons associated with it including shurikens, caltrops and poisons to complete their objectives inside China's kingdoms,Dynasty's and across the border into Japan and Mongolia as encountering their counterparts they're including genghis khan's warriors who will need avoiding head on.