They Myst tabletop RPG, “Unwritten: Adventures in the Ages of Myst and Beyond”, has a Kickstarter going for the game’s first expansion!
https://www.kickstarter.com/projects/inksparkgames/unwritten-modern-dni-sourcebook?ref=nav_search&result=project&term=unwritten
You can get the original book as part of the Kickstarter or at the link below;
https://www.drivethrurpg.com/product/146509/Unwritten-Adventures-in-the-Ages-of-MYST-and-Beyond?manufacturers_id=5893&filters=0_2140_0_0_0
The Mysterium this year had some big updates on realRiven including footage you can see at the link below, I made a list of timestamps for notable points of interest in the video. Unfortunately Rand Miller mentions the development of a Myst TV show or movie are back in a lull right now.
Richard Vander Wende the Co-director and co-designer of Riven is back at Cyan to help with the remake and was present to answer QA questions with Rand Miller.
https://www.twitch.tv/videos/1860698268
00:49:30 they show footage of realRiven and mention although not yet shippable it is now playable from beginning to end.
4:49:27 Rand Miller mentions that they will be able to dive a little deeper into Riven in some areas, that players who enjoyed Riven before will still have the same game but get to discover new things
4:59:27 They show some in-progress images from the realRiven, including places you did not get to visit in the original
5:13:05 they discuss expanding on the backstory for Riven
5:22:00 Rand Miller says that they may eventually explore some of the worlds mentioned in the original Myst but were not explored in Myst
5:36:50 discuss how Gehn may have figured out how to seal the fissure
5:39:20 Will explore more of what Gehn was doing during his 30 years being trapped on Riven
5:47:40 Book of Atrus is being printed in hardback with new revisions, only available at Mysterium right now but they intend to make it more widely available later.
5:51:18 Book of Marrim, no new updates on the Book of Marrim, it is more on the backburner right now
5:59:30 Talks about Myst TV series, he says development seems to be in a lull right now
6:05:30 They are expanding on the journals in Riven, including Gehn’s journals around 1 1/2 times more material.
Myst Movie Fans 