inkle studios (“80 Days”, “Sorcery”) recently released their interactive fiction authoring system, ink, as open-source.
It’s an awesome scripting language for writing narrative. Since I needed something like this and preferred ink to my similar home-grown, I re-implemented it in Java, and open-sourced the result. The implementation of ink is not yet complete, but it’s fully capable of use for complicated narratives already (+ I added some additional features that were useful for me, such as using reflection to provide direct access to Java class methods, etc).