Ok, so I was trying to find an opensource or fan made myst game to see if it was possible to port to the Dreamcast, and I found that a team is porting it and Riven to ScummVM! That means we can have it on Dreamcast!
I am having trouble finding where to get a reicent build from, but here is all that I have found so far.
The guys porting it.
http://clone2727.blogspot.com/
Some forum posts.
http://forums.scummvm.org/viewtopic.php?t=7132
http://forums.scummvm.org/viewtopic.php?t=2807
I don't know how much longer till both games are fully 100% ported, but they are getting very, very close to the end.
This has got me really excited as I loved myst on my Saturn and 3DO, and have since lost both systems and games over the years.