SEGA is going to be smart and cross promote the iOS game, Total War Battles: Shogun with the high selling PC title Total War: Shogun 2. So how are they going to do this? If you finish the campaign in the mobile game you will unlock a key-code, which will unlock the Sendai Clan Pack for Total War: Shogun 2 on PC (via Steam).
Sendai will give you +10 diplomatic relations and a 2-turn reduction time surrendering castles, -1 resistance to occupation and lastly -3 unhappiness from other allegiances. Not bad for it sort of being free, if you buy the mobile version.
Also the iOS game is getting a skirmish mode update soon. This will let you choose a difficulty level and get right into a battle, you will be able to complete the full campaign and use new legendary units. This is for people that don’t want the story in the way of their bloodshed.