I haven't been able to work a whole lot on the Echoes of Indigo project in the last couple of months, but I can at least share where I am with it. The general plan is as follows:
Step 1 was pretty easy. It's the big picture sort of stuff that you already have a good idea about going into a project. it looks something like this:
At the beginning of the story, most choices are to gauge who the players are, who they side with, and what their style and values are. As the story progresses, the players' values and allegiances are tested - looks like you're into cold efficiency, but are you so committed to it that you'll let families be torn apart in the process? What about your friends' families? What about yours? As the final conflict plays out, players should have a sense that they got what they wanted (assuming they went about it intelligently), but not without great cost. For this narrative that means alliances sacrificed, risks taken, and collateral damage.
Step 2 takes considerably longer, as it requires planning out how specific stats change, which characters are involved in different conflicts, etc. To that end, I've begun planning out one of the early confrontations with the alien race who intend to displace humanity - possibly for their own benefit, because of their sense of duty, or some combination thereof. So, basically...
The skeleton built in Step 2 is probably the most important step, and also the vantage point from which changes can be made most concretely. Rather than jumping straight into writing dialogue, I'd like to refine the choices themselves. To do this, I'm thinking I'll take some friends and have a D&D-esque play session with them where I describe the story and present choices. I've sketched out some ideas for how I'd represent the various player-visible stats to them, sort of like you'd have in a board game. For instance, Earth might have its own stat sheet:
After getting as many play sessions in as I can and tweaking the story choices accordingly, I'll flesh out the dialogue and do yet more testing! But for now, I'm furiously building out the skeleton to try to make the choices speak for themselves.