It means the upcoming Left 4 Dead spiritual successor cannot be played offline, even solo with AI teammates.
Back 4 Blood is an always-online game, developer Turtle Rock has confirmed.
Back 4 Blood is the latest game to insist on an internet connection even when played solo, and the news has sparked concern it may be unplayable if server trouble blights launch.
That’s what happened with the recently-released Outriders, which requires an internet connection even when played solo.