This server is called 99b99t and it is a new Minecraft anarchy world. There are no rules and no limits so players can do whatever they want. It is all about chaos and trying to survive while other people can attack or grief you any time.
The server runs on hard difficulty so mobs and players can be really dangerous. The world is fresh so there is still a lot of land to explore and build on. You can make a secret base or just roam around and destroy stuff. Nobody will stop you because that is the whole point.
It is online 24 7 and supports versions from 1.12.2 up to 1.21.11. So a lot of players can join with the version they like. If you want a true anarchy server with no rules this is exactly that kind of place.
