Interactive fiction is a method of telling a story which involves the reader's participation. This can range form simple choices (turn left at the path) to more complex, Role Playing Game-like rule systems.
Interactive Fiction subreddit on reddit.com
Adult Interactive Fiction Central a subreddit devoted to adult interactive fiction.
Informed AIF's review of several popular interactive fiction languages.
Inside Erin is an adult interactive fiction newsletter. They also have an extensive list of AIF games.
The Interactive Fiction wiki.
Stuffed, an adult interactive fiction about family members and a large, stuffed bear.
Adventures in Shatterstone is an adult adventure game in development.
Trap Quest is an extensive, graphics heavy interactive fiction.
Corruption of Champions is a popular flash-based interactive fiction.