Diablo II had two ways of playing online - Open BNet and Closed BNet. Open BNet allowed you to use your offline characters, but Closed BNet did not. The theor

Diablo II had two ways of playing online - Open BNet and Closed BNet. Open BNet allowed you to use your offline characters, but Closed BNet did not. The theory of the system was sound. The practical reason why Diablo II was a mess was because the game was buggy and trusted the client too much, making "Closed BNet" turn out to be not so closed after all. There is no technical reason why Diablo IV couldn't have been designed with the same two-tier system, they _chose_ not to do so.