Scribarchy
Scribarchy is a unique blend of multiplayer, collaborative, interactive fiction, played out in pre-built multiverses adapted from famous public-domain works. You can play the multiverses as-is, or you can propose short action ideas that a curator shapes into choices with real stakes, and the world changes permanently based on what everyone does. You pick from the choices in front of you, or suggest a new one for the curator to add.
Scribarchy is now in full production, running three completed public-domain multiverses: The Dream-Quest of Unknown Kadath (H. P. Lovecraft, 1926), A Princess of Mars (Edgar Rice Burroughs, 1912), and The City of a Thousand Domes (Andrew Lang's 1001 Nights translation, 1898). Each is a separate persistent world with its own geography, factions, and Roles, built on the same core rules.
Pick a multiverse, create a character, and see where your choices take you. Every path you carve stays part of the world for the next player who follows.