This is a modded civilization server called Adornment. The whole idea is that players group up and make their own civilizations. You can play with your friends or join a civilization that is already made.
PvP is allowed and griefing is allowed but only at a moderate level. You can steal stuff from other people and you can go to war with other groups. You can also decide to just build and play more peaceful if you want.
You have to get whitelisted before you can join and you need to download the modpack to play. The server feels like a place where players create their own stories with wars and alliances and random politics.
