More than fifty talented musicians sit down at the same time in fifty recording studios. Each has a different instrument- pianos, drums, flutes, violins, guitars, vocals, saxophones, harmonicas, you name it. This is all going to go through computers which are networked together. I don't know if an internet connection can be fast enough to coordinate what I'm about to suggest, but let's say it is and that these people aren't anywhere near each other. They are all wearing motion-capture suits, so that a video camera in each room can record movement to be applied to 3D models of the musicians.
The computer has an image of a virtual sphere, on which each musician is represented by a point. If two musicians are next to each other on that sphere, then they hear each other as though they were in a room together. See, each room has two or three computer monitors, positioned on the wall at the precise point where the musician would be looking if he were on the sphere looking at the respective person. On the screen is the live video feed of that performer, and next to it is a speaker so that each can hear what the other is playing. There's another speaker, not connected to any particular monitor, which very quietly plays everything which is no more than two points away, but still close enough to be relevant.
Once this is all set up, they just start to play.
No one is given any direction in terms of who starts or what key to be in or what style of music to play. They just listen to each other and figure it out as they go. They play for fifteen minutes or so, and leave.
Then the animators come in. They smooth out the motion-capture data, and integrate all the facial expressions in.
Then it's turned into a first-person exploration game. You start out from a point on the sphere of your choosing, and then you can walk around however you like, in 3D, as the recording plays out. Obviously, surround sound is recommended. The volume of a musician depends on your distance from him, and the musicians are spread out really far so that clashing performances are kept to a minimum wherever you go. (The specific distances are tweaked by a "composer" after the recording.) There's a thick fog, so that visibility is tied to hearing. You can go through the music over and over, each time taking a different path and getting a different experience.
This is not the sort of work which can be achieved overnight. It could take years of experimenting with styles and techniques and relationships and positions on the sphere. And even after all that, it'd probably be very flawed. But I think that's part of what's cool about it. It's more pure music- the conflicts and admirations between musicians, fighting with each other and hugging each other via music. And you can look at the faces, see how they react to each other, try to imagine what this musician heard in that one's performance which inspired him to play this. It's the sort of thing you could play over and over for years, and still find new depth in.