Twine is a tool for building interactive, nonlinear stories that are implemented as web pages. It uses a combination of a graphical editor (which lets you create discrete passages and hook them together (it also generates flowchart-like graphs of passages to help you keep track of the structure)) and an HTML compiler on the back end. Includes a simple scripting language to add state and conditionality to the story. If you can write a couple of pages, you can build interactive fiction that you can play in a web browser with this tool. Uses Tiddlywiki-like markup syntax.
William Gibson's self-destructing work Agrippa has been reconstructed from one of the original diskettes (it was never actually released) and put online as a simulation.
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