Twine - Twine is an open-source tool for telling interactive, nonlinear stories.
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
Arcweave - Arcweave is the first browser based cloud professional tool for game and narrative design.
Manuskript - Open-source tool for writers.
Dialogue Designer - An easy to use but powerful tool for creating branching dialogues for games.
Novlr - Online word processor and organizer for novel writing.