MineX SMP is a survival server that feels like it wants you to actually live in the world and not just speedrun it. It runs on 1.21.11 and it uses a huge 8K by 8K custom survival map made for exploring and settling down for the long haul.
The main thing people do here is Towny. You can claim land start a town build protected areas and team up into nations. It also leans into player made politics and a survival style economy so towns and groups can grow over time.
There is also a custom enchant system so combat mining and gear progression has more options than normal. The server is still being worked on and new areas and systems keep getting added as it develops.
