Will I miss out on anything in the single player game if I don't play Factions? No (except having fun). Now, that said, we've put a lot of thought and effort into Factions. It's not just a mindless one-off from The Banner Saga. Factions takes place in the same world, in a city that is part of the single player game and when events happen in single player they'll affect the world in Factions. As we create new system for the Saga we'll be testing them through Factions, so things like playing against the computer will appear in Factions as we work out the code, and the story will all tie together.