The rules of the culling game, which is part of Kenjaku/Noritoshi Kamo/Suguru Geto's plan, is a bit confusing. But I think right now, they are basically working on 2 things - enter the culling game to save Tsumiki and free Gojo to stop all this nonsense since they believe he's the only one who can.
Now someone has to explain the latest chapters to me please cuz I am so lost ( ̄∇ ̄")