Sir Pootis said:
They take away the typical story mode and replace it with 'Empire mode'. Basically, you're given a map of China or Japan made up of various regions. You choose from a bunch of selected periods/eras/events (e.g. 'Yellow Turban Rebellion, Rise of Cao Cao, Incident at Honnoji etc.) and then select who you want to play as. This could be a major faction, a minor faction, or a faction you can create. One of the main draws of the series is the ability to create your own characters and factions.
So basically they're the Musou equivalent of grand strategy games like Civ and Europa Universalis but nowhere near as deep or complicated.
Gameplay is typical Musou fare where two sides try to take control of the battlefield. You can control your officers, give orders, and in some games utilise strategies and formations which consist of various things such as fire attacks, blocking reinforcements, and giving temporary buffs to allies. The game typically ends once a faction controls the entire country. Action outside of battles consists of researching and creating items, forming alliances, committing various acts of espionage, holding war councils and other political stuff.