How much do you think a story can branch? How divergent can a story be? And should the branches generally conclude around the same point/should they be given the same amount of effort? Could some diverging storylines involve genre shifts or large toss-ups to story structure?
Detroit: Become Human was a great example of that. Its branches were beyond any games’ with a feeling that choices had impact.
If you want to look at games and learn how not to branch, well… look at Telltale’s recent games.
As much as you allow. But fanfic exists, though. Headcanon is also an undeniable psychic force.
As for genre shifts, eastern media often ends up in a genre shift despite being linear, both brings good and bad.
Short answer… A lot.
There’s loads of different ways to write an interactive fiction novel, and while a lot of CoG and HGs are more linear, one of the more traditional ways of writing interactive fiction is in the old Choose Your Own Adventure style, where essentially every single choice you make will lead you down a completely different path.
There are advantages and disadvantages to the different styles though. More branches obviously add to a game’s replayability, but it’s also important to keep in mind that having the game branch a lot generally means that while the game’s word count might be very high, the actual playthrough length will be quite short… Unless you include a lot of dead ends in the game, where making the wrong choice just leads to the character dying… But in my personal experience, people don’t really seem to like this. It’s preferable if all the branches have a more or less equal amount of effort put into them, which can get very complicated when you have tonnes of branches to work on.
Essentially, the amount that a choicescript game can branch is limitless. But the more branching you have in a story, the more important it is for the author to carefully plan the game out to make sure they know exactly where every branch is going.