I’ve just make my document grow with my narrative design needs.
One think I’ve learned is to make tables of everything. I’ve divided my game into bits, every bit can be gameplay, cinematic, dialogue or scripted sequence and I have a table with every bit defined: a code name, dependencies, summary, description from player’s point of view, location, enemies, characters, new character if there is, design intention and story beat.
With this, I can follow the story from the beginning to the end.
Then, I have some table views and formulas with specific data from the bits.
I have formulas to check how many quests happen in X location, or how many quests are about a specific type of objective. All of that to balance the game.
Hope it helps you. If you find anything interesting tell me, please.