There was an up and comer a few years back called Blue Mars, that was shaping up to be something really cool. It allowed content creators a great deal of control over their virtual landscapes.
But, for some reason they abruptly changed direction to some kind of weird mobile avatar creator on mobile and shut down shortly after.
That could have been it, but when they pivoted they had a very complete beta product. Probably more to do with investor pressure or something along those lines.
I think Blue Mars was started when there was a huge surge of them after Second Life took off. Even Google and others were developing something in the space.
But, for some reason they abruptly changed direction to some kind of weird mobile avatar creator on mobile and shut down shortly after.