Here's some realtime rocks I sculpted for an unannounced/cancelled indie game project in 2018.
Rocks were sculpted in Zbrush, bakes and materials were created in Substance Painter and then imported into Unreal Engine.
I then create a procedural moss shader to automatically generate moss using the classic technique of masking the top most facing faces using vertex/pixel normals and a dot product. It's also further enhanced by sampling prebaked AO maps generated using Lightmass and vertex painting for further control.