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".
World of Warcraft
Seven expansions have been released: "", released in January 2007; "", released in November 2008; "", released in December 2010; "", released in September 2012; "", released in November 2014; "", released in August 2016; and , released in August 2018. Players are not required to purchase expansions in order to continue playing; however, new content and features such as higher level caps and new areas may not be available until they do so.