Follow these simple steps to get the free serial key for Diablo lllbr br Diablo III is a dark fantasyhorror-themed action role-playing game by Blizzard Entertainment, making it the third installment in the Diablo franchise.The game takes place in Sanctuary, the dark fantasy world of the Diablo series. Sanctuary was saved twenty years prior by unnamed heroes in Diablo II. Having survived that onslaught, Tyrael rewarded the heroes by sending them to safety. It is up to a new generation of heroes to face the forces of evil threatening the world.