RefinedVanilla is a true vanilla anarchy server where you can do almost anything. The only real rule is no hacked clients so it stays fair in that way.
People build huge bases then other players can find them and wreck them. You can explore far out and just mess around with whatever you want.
It also runs custom software that adds multithreading so it can handle high player counts while still feeling like vanilla. Nether roof is enabled and chunkloaders work and lazy chunk cannons work too.
