MC Bloodlines is a hardcore SMP server that is all about invite only survival and building real civilizations.
You cannot just join out of nowhere. Only players who are already inside the world can invite new people. This makes the population feel more like real life and it keeps trolls away because everyone is kind of responsible for who they bring in.
The server has secret tweaks and custom mechanics that nobody explains. There are no guides. You have to discover everything on your own by paying attention and trying things. This makes every day feel new and it rewards players who are patient and really dedicated.
There is a built in clan and family system so you do not just spawn alone in some random hardcore world. When you join you are part of a clan and a family and you are dropped into a story that started before you and will keep going after you are gone.
Most clans are looking for more members right now. If you want to join you need to talk to current players and see if someone wants to share their personal invite code with you and then follow the wiki instructions on how to use it.

