This sounds painfully simple, but, believe me
- Commit to story early on
- Develop and modify the story with the technology
- The story is never done as long as technology is still being developed
In the end, if you want a narrative-based game - regardless of format - there needs to be commitment to the story from the very beginning. The first point is absolutely critical. If you expect a game designer to also design systems and the like, that is fine, and given budget constraints, typically inevitable. But if you commit to a narrative early on, that - as much as platform - helps determine system requirements. I know that the programmers that read this may raise an eyebrow, but when you know the story, you know what sort of AI infrastructure you need, what sort of animation and facial systems required.
Story can help you list what technological innovations you need to work on, and what fanciful systems that the game will need.
Hurm...let me ponder more...I may come back to this...