I read this a few years ago - it was the first piece of multimedia fiction that I had ever read, and it inspired me to go in search of internet-based fiction, which ultimately led me to IFDB.
17776 makes use of different formats - text, video, gif, even a calendar - to tell a rather bizarre but genuinely fascinating and original story. Reading through the first chapter in particular made me feel strangely unnerved and wonder what was going to happen. I don't want to give too much away, but it's set in the distant future when human life is extraordinarily different, and is told from an unusual perspective.
Although it's relatively low on the interactive elements, the multimedia aspect of it will appeal to people interested in new storytelling formats.
In this Twine short story, a great sense of atmosphere and suspense is created, not just by the use of images and sound, excellent as those are, but by thoughtful use of links: links that change text when you click on them, links that trigger a time delay, and changes of layout. I would have liked the plot to have developed more - it felt like reading the first half of a story.
Nevertheless, this is a good example of what I would consider multimedia fiction, where the interactivity provided by Twine is used not to give the reader a choice of narratives, but to provide atmosphere and to move the story onwards.