Find The Future is a fascinating online game from The New York Public Library.
I haven’t quite figured it all out yet, but I played long enough to be able to say it is indeed fascinating. After a quick registration process, you pick an “artifact” from the library. Each artifact has a very engaging interactive display sharing information about it. Then you a given an unusual writing prompt related to the artifact, and you have to write a story. There’s more to it than that, but it is intriguing and accessible.
The big drawback that I see to it, though, is that though your stories are saved, it appears that only participants in the game can read them. In other words, you can’t post a link to it elsewhere that would allow people to read it without registration. At least, it doesn’t appear to me that you can — please let me know if I’m missing something.
Again, there’s more to the game than what I’ve written, but it is definitely worth a visit.