There’s a logic to making Midgar the first “book” - not only because it’s so clearly self-contained, but because a smaller portion of the game would let them combine episode development with basic “infrastructure”, the engine, character design, combat.. since that’ll be out of the way, the rest of the project could go more smoothly..
No idea how they’ll divide up the rest, though.. it helps that the “open world” map was very gated.. but for being an admirer of the original game I’ve never made it past Rocket Town..