On the other hand, it's certainly more engineering to have to build a custom format. I implemented a story engine that compiles to behavior trees, and then subs

On the other hand, it's certainly more engineering to have to build a custom format. I implemented a story engine that compiles to behavior trees, and then subsequently to a small instruction set in this past year and, well, we're talking about three months to go from having no technology to having a pipeline capable of complex scenarios. But I came out of it with a much more competent strategy for addressing assets than anything I've done in the past, so I'm not complaining. It is the core technology of the game(choice driven, text simulation) so it needed a big investment. And the game is going to have content updates, which makes save games terrifying; In the end, I designed it so that it has episodes and restarting the game starts it from that episode so that I don't have to worry about massive amounts of persistent state getting permanently corrupted.