Here in the UK we use to have a TV program called Tomorrows World. It ran from 1965 to 2003 and looked at new and upcoming technologies, always through rose-tinted goggles no matter how unfeasible or flawed the idea was. In the late 90's they featured an item on a virtual reality prototype, which was basically a large transparent hollow sphere the user stood in whilst viewing images projected onto the outside of the sphere. The demonstration showed used a monster-less e1m1 as the environment in which user moved around, or should I say 'shuffled' around.
I've been telling my friends about this for years, but could never find any evidence of its existence. Not remembering it's name didn't help. I'd got to the point where I was beginning to ask myself whether I had imagined the whole thing.
But no, it did exist and I've finally found proof. Judging from the video though, I wouldn't want to spend too much time in something like that without having concern for my hearing. Wireless controllers and headphones would be a wise idea, but this was the 90's (....actually I'm not sure when these first became available).
Anyway, I present to you the 'Cybersphere'........
https://www.youtube.com/watch?v=BGVu7pWQIrs