I just managed to get the base done for our modular cave system. I built a pretty simple model kit that works with the UE grid. I´m also planning to figure out a faster way to generate cave systems, maybe with splines or procedural tools. Then I made a master material for rocks so they blend two different rock textures, a sand texture to blend better with the ground, water leaks draining down and a macro normal map to add vertical details. I also made one material for the cave ground too. Its blending three different textures and I can also vertex paint water puddles there too. All of these blendings uses vertex paints. All of the textures are made with Substance Designer and ZBrush. I also found out a pretty cool trick to use procedural foliage spawner system for the cave rocks, scifi fungus and bigger rocks. It gives a pretty good base to start with and then I can continue with the foliage paint tool.
Here is a video of the space and cave environments: Planetrism - The Cave - YouTube
You can now also find us on Cartdge https://cartrdge.com/magus/projects/planetrism And like always, more shots can be found on our ArtStation: https://www.artstation.com/artwork/qwd3L