I like the term "digital reality"

I chose the name "virtual realty" as a humorous pun, but It's seems clear to me that we are moving beyond "virtual space" in just the same way that bitcoin is not a "virtual currency": because it is not controlled by any one entity, it can be said to obey "natural laws" (albeit human-chosen ones) and thus, it can be argued to be "real" rather than "virtual".

As for 3D space, I don't think it's much different from 2D space: you can just extend space-filling curves to 3D space.

For a few weeks, I have been working on a new protocol on top of the Bitcoin blockchain. It is similar to Colored Coins, but instead of defining a new fungible asset on top of bitcoin, it defines a non-fungible asset in the form of a set of points in space.

I have written a whitepaper that describes this protocol, along with a proof-of-concept implementation in PHP. I have also used this implementation to compute the cadastral map of the Great Pizza Transaction and rendered it as an animated GIF.

Right now, I'm in the process of writing a daemon that keeps track of the cadastral maps of a set of spaces in real-time, including backtracking in case of forks and fast trustless sharing of new spaces. But the hard part is defining a different protocol to allow for the specification of space contents: the idea is that the owner of a piece of space can sign a message to specify its contents and broadcast it to a peer-to-peer network.

I'm a bit stuck on this problem of space contents, so I was wondering if anyone here would be interested in discussing it with me.