Wondershare PDFelement - All-in-one PDF editor
Twine - Twine is an open-source tool for telling interactive, nonlinear stories.
Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.
Ink by Inkle - ink is a popular open source scripting language for branching stories, designed for writers
Foxit PhantomPDF - Edit PDF files with our feature-rich PDF Editor. Download Foxit PDF Editor to convert, sign, scan / OCR & more. A speedy PDF Editor alternative to Adobe Acrobat.
Quest - Quest lets you create sophisticated text-based games, without having to program.