I can't believe articy:Draft X doesn't seem to have been mentioned here. I'm making an RPG with Disco Elysium-style branching dialogue and articy is a godsend, especially if you're writing games with open-ended, branching stories.
articy lets you write dialogue and plot timelines by means of a 'flowchart' simply called the flow, where you can also do simple scripting by attaching code to flow items, and also comes with a database to help you keep track of documents, images, music, locations, people, items, etc. (which can also be tied to modules in the flow). Best of all, you can export your project directly to Unity or Unreal.