Adding dialogue trees to your game has always been a non-trivial task until now.
Welcome to Yarn. Yarn simplifies adding NPC conversation to your game by integrating with Twine, an open-source solution for creating dialogue trees (or interactive non-linear stories as they put it).
Yarn doesn’t stop there. Yarn includes a very usable/customisable GUI that uses standard Unity 4.3 sprites and text meshes to display the conversation.
Yarn also handles Loading and Saving of the conversation history.
So give yourself a head start and get your game characters talking with Yarn!