I found a community event server that runs a 30 day world with only 16 sessions. It is limited slots so you have to apply to get in. The world border starts super small then it grows bigger each day and it ramps up fast.
The whole point is meeting people doing in game events and making cool builds. It uses a very light Vanilla+ modpack so it still feels close to normal Minecraft.
They do three of these seasonal Civilization style servers every year in spring summer and winter. Each season is a fresh world where people can make alliances and rivalries.
The rules are simple. No stealing no griefing no cheating and no RDMing.
