If you want a single-focus game, you have to be pretty hardcore about telling players to app within that focus (I have learned this lesson from frustrating past experience). I personally don't see this as limiting. It's being clear about the kind of stories you'd like to tell and what you'd like to provide for players. I don't actually like games that try to be ALL THE THINGS and, unless they have a huge playerbase, I feel like that attitude becomes self-defeating.