Diablo 3 is the first game to render Diablo 2 obsolete.
With Diablo 2 and its 2001 expansion, Lord of Destruction, Blizzard set a standard for loot-based action RPGs that everyone else struggled to meet. There were better looking games over the course of the following decade, but almost none had the same unifying aesthetic, or the sense of place that Blizzard built into the wilds surrounding Khurast or Lut Gholein, or Hell, for that matter. Few could match the world-building that Blizzard wove into every corner of Diablo 2, from weapons to monsters to stashes and chests. And every game from the last 11 years, even the Torchlight series, created by veterans from Diablo 2 developers Blizzard North, failed to build a loot system as persistently rewarding and aggressively addicting.
Other games did some things – well, if not better, perhaps newer – but Diablo 2 has never felt irrelevant. With Diablo 3, Blizzard has taken the fundamentals of the franchise, broken them apart and rebuilt them into an action RPG so refined and compulsively playable that it's done the unthinkable: It's finally rendered its predecessor a footnote.