Copyright is always about distribution. So yes, you are allowed to fork, but you are not allowed to distribute the copyrighted content to other people. And with the No Derivatives clause you are also not allowed to change it. You might be able to stay in the gray are by telling everyone “build it yourself”, but nobody would be allowed to package it either.

As far as I can see the company behind it (Starfish Neuroscience) is not affiliated with Valve in any way? (Aside from having the same CEO)

Yperating System?

Seriously, for me a “China scientist” is someone doing research on China, like a space scientist would do research on astronomy and similar. But I’m not a native English speaker, so, idk