Undum is a fascinating new open-source framework for interactive narrative designed for HTML 5 and CSS 3. Though it retains the ideas of nodes hypertext narrative and of rooms or spaces from interactive fiction, clicking a link to leave one space and enter another simply adds more text to the ever-growing main narrative. This design encourages the reader to go back and read the narrative as a cohesive whole rather than thinking of it in terms of small narrative bits strung together. It also seems to encourage shorter texts; a novel-sized text which on a single scrolling page, even if it were presented in small bits, seems cumbersome.
Links disappear once you pass them to prohibit the reader from retracing her steps, and the author can make other text disappear when a new node is entered. This lets the author ask a question,
"Do you slay the dragon or do you run away?"
and then, having received the answer, efface the stage business of the question and replace it with a seamless continuation.
Undum does not limit the author to branching-narrative links. It also offers a dynamic character state, or list of constantly changing attributes, which can be influenced “action” links. These links the reader in the same node—or “situation” as Undum calls them—but allow for changes to character states, for example raising experience. There is no explicit support for dynamic links or guard fields, though adding them should not be difficult.
The system, which offers a nice tutorial, strikes an interesting hybrid balance between the classic hypertext fictions and IF.