[zvqcMMV6Zcr]

The term "derivative work" covers a lot. For example all fan translations are one and all content stored on movie subtitles sites is by definition illegal. I don't know about those particular VR mods but in general case it is easy to show that game mod is not a standalone work and counts as derivative work, so game developer can limit the distribution however they want.

[marak830]

I think it's more a dependency and less a derivative (there isn't any source code/game objects being distributed via the mod as far as I can tell.)

I would be very interested to see how a court would rule on this, as AFAIK such as Lexmark v. Static Control Components, you can modify products you purchase, but how much weight would the TOS really hold?