Basically the title. When games shut down, communities will typically host community nights during the server’s final hours, cramming in as many nostalgia-fueled games as they can before the inevitable shutdown.
I can think of little that would be more heartbreaking than if all of the classic Halo games shut down on the same night, splintering the community’s efforts to play each game until shutdown. I know I personally want to spend time on every game right up until I get a connection error confirming that the servers are gone.