Just Another Hardcore is a hardcore survival server where you only get one life and when you die you are gone forever. It aims for a mostly vanilla feel but it adds a few changes that fit the hardcore vibe.
The world never resets so every base and every mess you leave behind stays. It has statistic leaderboards and player heads can drop when someone dies. There is also a way to will your enderchest to someone if you die and there is a way to disable phantoms.
The server is semi anarchy so you can do what you want but there are some limits to help keep the world ok like lava casting being disabled and wither spawning near spawn being blocked. It runs on 1.21.11 and it supports joining on 1.21 plus.
