There will be subtle textures, but they will be close to flat. The dirt in the forest shows the approach I'll use. I'm trying to work distance tiles into the set, but I'm still unsure how I'll make them. To create room in the main set, I'm moving less vital pieces to the secondary sets. For example, the slope is 4:1 and I have corner pieces for every step of the slope for every direction. That comes to 32 corners! They all don't need to be in the main set.
With secondary sets I want to add a variety of decorations. I've been considering glowing crystals as a light source. I also want to make calcium formations, mud, pools, plants, dwellings, etc.. There may be several secondary sets allowing vast differences between sections of the cave system.