This server is called CaveMC and it is on Season 2. It is a semi anarchy survival world where the whole overworld is underground. There is no surface at all. Everything is caves with different biomes and resources and structures all around.

The server feels like enhanced vanilla and it is really brutal. You have to be smart to survive because other players can fight you and the environment is always dangerous. It is not a peaceful server so you need to be ready for pvp and tough survival.

They also have a new Wasteland Dimension that opens during this season. It has special gear you can only get there and giant mega structures to explore. There is a unique currency in that dimension so it has its own economy and trading style. There is also a new spawn area made for this world and a custom generated map with special features.

Overall this server is all about living and fighting under the ground with no sky and exploring a crazy new dimension with strong loot and big secrets.