Naninovel
A commercial Unity framework with a script language, characters, backgrounds, choices, saves, rollback, localization, voice, and customizable UI.
Why use it
Mature built-in systems reduce repeated engineering while writers deliver scenes continuously through text scripts.
Where it fits
Use art, animation, audio, levels, and narrative to make the game easy to read and its world convincing.
What to check
It follows Unity Asset Store licensing and has a broad footprint; deep UI changes, architecture integration, and upgrades require budget.