Blizzard Entertainment today announced that World of Warcraft has sold through more than 600,000 units to customers in North America, Australia, and New Zealand. The fastest-growing massively multiplayer online role-playing game (MMORPG) has also shattered all previous concurrency records in North America, achieving over 200,000 simultaneous players during the holiday period.

"The public's response to World of Warcraft has been simply amazing," said Mike Morhaime, president of Blizzard Entertainment. "We are very proud and excited to see such an overwhelming demand for the game, and we hope that the enthusiasm continues to build as we further enhance our online service."

Over this holiday season, demand for World of Warcraft was so great that retailers estimate that nearly all remaining supplies of the game sold out across North America, Australia, and New Zealand. To accommodate the increasing number of players eager to join World of Warcraft, Blizzard will be bringing several new servers online. After a short and successful testing period to ensure server stability, the company also plans to release additional units to retail outlets nationwide.

To support the growing population in World of Warcraft with regular content updates, Blizzard Entertainment is aggressively introducing new features on an ongoing basis. These updates will keep the game fresh and exciting, rewarding continuing subscribers with new experiences and enticing prospective players to join in even greater adventures.

Several features have already been introduced since the game’s launch just over a month ago, and many more are planned for the lifetime of the game. In the near future, the promised Player-versus-Player (PvP) Battlegrounds, which will pit Alliance and Horde players against each other in a hotly-contested battlefield, as well as the PvP Reward System, will be revealed.