Description
Undum is a tool for writing hypertext interactive fiction. It has some unique features and a visual design that encourages narrative games.
Hypertext interactive fiction is the digital equivalent of the Choose Your Own Adventure (CYOA) books that were popular in the 1980s. The story is told in chunks, and you select from a range of options to move it forward. Unlike the book form, however, the digital form gives you far more flexibility to tell rich stories and introduce more interesting game elements.
(Source: http://undum.com/games/tutorial.en.html)