Campaign Creations

https://www.youtube.com/watch?v=dDLog0Vqpo4
This is a Unity tech demo from a couple years ago. I came across it while binge-watching short films. The animation is really cool, and all the art assets are available for free: https://blogs.unity3d.com/2015/06/24/re ... lacksmith/

There's also this one, called ADAM:
https://www.youtube.com/watch?v=HaOOWK14pgs
Art assets: https://unity3d.com/pages/adam

ADAM: Episode 2
ADAM: Episode 3
EP2/EP3 Assets

It is possible to export from unity archives into a standard format, for the curious.

They also don't care if you use it in other engines. But they don't have a unified agreement and people can insert their own dickery per item.