Undum is a game framework for building a sophisticated form of hypertext interactive fiction. If that means nothing to you, then let's go back a few steps. Remember those Choose Your Own Adventure, or Fighting Fantasy books? Where you got to choose what your character does next? Well if you think of that in a web-page you have hypertext interactive fiction, or HIF. Instead of turning to a particular page, you click a link, and the next bit of content appears.