The gamemode is called UHC and its a survival gamemode where you have a short grace peroid and you get released into a large plain, like a survival world, and you gear up like you are in normal survival world, then after many minutes all surviving, players try to go back to the center of the map, meeting other players on the way, killing them, and getting more and better loot, letting one last player to come on top.
Doing a little research can help find more to this gamemode, I remember an old youtuber used to play it alot, TapL is his username, also he played variations of it too, custom modes of uhc, like random uhc, mining a random block can drop a random loot table of any sorts, this would be awesome gamemode to be added, thanks!
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