I walked to work this AM listening to the soundtrack to Riven and realized just how much impact the music has on the game experience. Though the gameplay of the Myst series really can be annoying - the experience of wandering around and just being immersed isn't. The tight connection between the music and the visuals really made the experience a "real memory" versus a "game memory".
There has been a lot of news concerning Mudpie - the next Myst. It's a massive multiplayer online game that will allow users to build communities and other items online together and also explore the world. I wouldn't expect any hack and slash - though I would expect music trades and other storytelling tools for Mudpie. Let's hope the name is reflective of making mud pies with friends when you are little.