Hyper-G was a distributed hypermedia system developed at the Graz University of Technology in Austria, overshadowed by the World Wide Web and now long forgotten. See this PDF overview article: Hyper-G: A Large Universal Hypermedia System and Some Spin-Offs.
The big difference between [the WWW] and Hyper-G is Hyper-G's distributed link server. This
server keeps track of all the relations (e.g. links) between Hyper-G objects, allowing for automatic
maintenance of the information network. For example, when an object gets deleted, the link server
will be able to find and delete all links pointing to the object. In contrast, in Gopher and WWW
there is no easy way to find out what other documents are pointing to a given document
Dear God that sounds horrible and amazing.
I'm glad it didn't catch on, but I really want to see it in action.