Warcraft
In 2004, Blizzard Entertainment moved the series away from the real-time strategy genre and released "World of Warcraft", a massively multiplayer online role-playing game (MMORPG). Requiring a subscription fee to be paid to play, it also introduced regular additional content to the series in the form of patches. "World of Warcraft" gained popularity worldwide, becoming the world's largest subscription-based MMORPG in 2008. The game reached a peak 12 million subscribers worldwide in October 2010. "World of Warcraft" has had seven expansions as of 2018. During the production of "", Blizzard co-founder Frank Pearce stated that "If there's a team that's passionate about doing another "Warcraft" [real-time strategy], then that's definitely something we would consider. It's nothing that we're working on right now, we have development teams working on "", "", "Diablo III", and when those teams are all off the projects they're working on, they'll be intimately involved in the discussions about what's next".
Role-playing video game
Among the best-selling PC RPGs overall is the massively multiplayer online game "World of Warcraft" with 11.5 million subscribers as of May 2010. Among single player PC RPGs, "Diablo II" has sold the largest amount, with the most recently cited number being over 4 million copies as of 2001. However, copies of the "Diablo: Battle Chest" continued to be sold in retail stores, with the compilation appearing on the NPD Group's top 10 PC games sales, list as recently as 2010. Further, "Diablo: Battle Chest" was the 19th best selling PC game of 2008—a full seven years after the game's initial release; and 11 million users still played "Diablo II" and "StarCraft" over Battle.net in 2010. As a franchise, the "Diablo" series has sold over 20 million copies, not including "Diablo III" which was released for Windows and OS X in 2012.