I’ve been using Twine as a prototyping tool for graphical game development. I wrote a blog post about it that I thought might be of interest to some folks over here too.
There’s a story progression in Ridiculous Fishing?! I stopped playing once I got to the Maelstrom because (as far as I could tell) no story had happened yet; I figured that the “Tale of Redemption” subtitle was just an ironic joke.
I’ve also used it as an organizational tool for novel writing: doing a rough outline of the narrative and having other boxes for characters, places, facts, etc.