Blizzard admits that completing the beta version of Diablo 3 is well…easy.  However, they assure fans that the actual game will be much, much harder.  In fact, in the video below developers explain the difference between the game’s four gameplay modes of Normal, Nightmare, Hell, and Inferno.   Within the “Inferno” setting some bosses will be so difficult that it may take up to an hour to defeat them even with a team of players bashing their heads in.