It's a fake OS in the sense that it's actually an application, not something that can be ran as an operating system like Linux or Windows. I've been a bit careful with my wording when advertising this, I wouldn't want to give the wrong impression.
Calling it a fake OS was, IMO, s great choice for avoiding confusion. Maybe something like Concept-OS or Desktop Environment Mockup could be good names if you want to be fancy.
How hard would it be to include a terminal emulator? You’d get a lot of functionality for free, there!