Some progress has been made. I worked on the textures for the land, and played with Composite Nodes in order to soften the billboard issues of the clouds due to the Atmosphere not supporting faces other than Solid.

As you can see, I also played with particles in order to start to grow an ecosystem. For the moment, the trees are only "placeholders" quickly modeled, the only attention I paid is about the range of colors. I wanted to depict somehow true colors as seen in wildness.

I also simplified the water surface: it is now a single plane. Enough for the moment.