https://www.pcgamer.com/the-myst-25th-anniversary-collection-will-bring-the-full-series-to-windows-10/

2018 marks the 25th anniversary of the great point-and-click adventure Myst, and to celebrate the big birthday Cyan announced last month that updated versions of all the games in the series would be released later this year. Today the studio launched a Kickstarter to support that effort, with details on what's coming—seven games instead of five, for one thing—and how they're being updated. 

Myst, Riven, and Myst 5: End of Ages are readily available on Steam and GOG, but Myst 3 and 4—Exile and Revelation—for some reason are not. Cyan said in the Kickstarter pitch that it's been working for awhile now to gain the rights to release all of them, and it's "finally managed to talk with all the right people in all the right places to garner funds to make it happen."