The NPD Group rolled up multiple SKUs of the massively popular PC online game and its expansion packs since its November 2004 launch to arrive at the 8.6 million figure. The statistics provided by NPD included the base World of Warcraft, plus the Collectors Edition version, the expansion pack-bundling Battle Chest, and the two standalone expansions: The Burning Crusade and Wrath Of The Lich King.
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