Unfortunately, Diablo 3 can't be played like you did in the previous version of Diablo because Diablo 3 depends on an Internet connection. Everything you do is server-side generated and every item it drops has unique stats because of the engine they created. The only way to play Diablo 3 in offline mode is on the Playstation or Xbox platform.
There was an attempt to create a Diablo 3 server, but Blizzard blocked it and the only way to play it is while you are connected to the Internet.
