Sheltercube is a semi vanilla smp that feels like a forever world. I watched it grow for about two months and the place already looks super cool.
There are big community projects and a small group of active players. People build bases and set up shops and work together on large builds. It feels kind of like a Hermitcraft style world with a shopping area and fun redstone stuff.
The server is really focused on community. Everyone seems chill and likes to play at their own pace. It does not matter if you like building or redstone or exploring or even telling stories. There is room for different play styles.
If you want a relaxed survival server that is trying to last a long time this one fits that vibe. You can join and help shape the world as it keeps growing.

