This particular implementation might not be super-useful as a desktop environment, but I do believe that user interface innovations from games (especially those that require fast user response like FPS games) could act as an inspiration for a very efficient type of desktop interface.
One thing I really found useful was the radial menu upon right-click in the NWN1 game (the straight menus usually triggered by the mouse do not make much sense). Something similar would definitely be useful on a desktop too and might also be more touch friendly.
A 3D "maze" could for example be a rather handy way to organize groups of tasks (a "documents" room, a "browsing and IM" room etc...) for some people with a spatial memory, but would probably just turn confusing for most people.
One use for this could be simulated environments for teaching. For example if you're training to become a network engineer, a mainframe room could be simulated in 3D like this and every terminal could be a virtualbox session. Some thing like this would help train students on very expensive hardware in restricted areas.
I'll admit, realistically...not much real-world usage. That being said, its a very nice demo, and I'll probably end up installing it when Fedora switches to Wayland just to have it as an option at the login screen to play around with from time to time.
My kudos to the developer for having the idea and implementing it, it is very original and very creatiive =D