m. c. de marco: To invent new life and new civilizations...

Via gamebooks.org: Twine is a free graphical gamebook editor for Windows and OS X, with a command-line version called twee. It looks polished enough to save me the trouble of writing my own.

See the old Gimcrack’d page for examples of twee-generated hypertext fiction.

Update

Twine now comes in two versions, and twee in even more.