Hm, it was not really just that, a demo. I remember some fine screenshots of editors, node based shader editors and much more.

I dont want to say that you are totally wrong. Sure it was not a completed engine but it must have been more than only a NVidia demo. Otherwise they could not sell it to those publishers.

At the end, I agree with Broozar. There are fine and fast growing alternatives at the moment. The engine landscape is very exciting right now.