Lots of people wrote about this, but Vertelemming was the most appropriately obscure, so gets namechecked. He said "You are returning. The stream in the Cleft is returning. The cavern is returning. Uru is returning." And so it is. It's a free server, so you can just go play and donate if you wish. "We’ve opened all the Ages, and added most of the goodies in MO:UL. We’re referring to it as MO:ULagain—feel free to explore and enjoy," as they say. And here's three videos made in tribute to the game when it closed. Lost of footage of - er - stuff. Also, things.
Any Myst fans out there? I ask, because it's one of those nagging games which, despite its enormous success in its day, you never find a games journalist who's into them. Except Richard Cobbett, who probably likes one of them, because that's the sort of thing he knows. He's like that.