Separately, to clarify, "minimum specs" is exactly intended to set a baseline - i.e. a minimum - for what will run the software and do basic operations. In the game world it means you can run a game in low resolution and low detail and a low but playable frame rate. Since game content is more finite and specific (the developers know what assets are in the game, how much geometry is in a given part of a given level, etc.), and there is a minimum frame rate for human perception of interactivity (around 30fps, obviously higher is better!), it's fairly easy for game publishers to say what the minimum hardware should be.
Open-ended creativity applications are much harder to specify min spec for because it depends dramatically on what you are doing with it. A simple scene with a few single objects or small populations and basic shaders is going to be very different from a complex scene with multiple levels of displacement, intersecting v3 cloud layers, large populations, etc. Sometimes it's not necessarily intuitive what will be demanding in Terragen, not because it's not logical, simply because it's hard to intuit what takes a lot of calculation without knowing the internals of how Terragen works. We are working to make that kind of info more clear and available.
In the case of this scene, each of these balls uses a shader network with more than 30 (and in one case more than 40) nodes. They're beautiful materials, but that's a lot of nodes to evaluate for the path tracer, I think. Many similar scenes in other apps would not be using any procedurals at all - or very few - mostly relying on image maps. In the case of image-based materials the lookup is quite simple, just checking values in a texture map, rather than calculating a bunch of math to figure out pixel color for 30+ nodes in sequence.
- Oshyan