Example of faction goal ? It can be hunting/find something, crafting, building...It depends. Like in Skyrim and Fallout 4. It is not necessarily against other faction, it can be an weekly event with different level. In fact, another way to do it is to create event with limit by factions, forcing some factions to be ally or enemy. For example, ressource A and B are available. But faction C and D need A, Faction E and F need B, depending on the goal they have. A sort of marketplace of factions. I think it is one goal of Fallout, to understand the need of the other factions. By doing faction quest, player had bonus and reward only available for this type of mission.