While Blizzard's World of Warcraft remains the undisputed king of the massively multiplayer online market with more than 9 million subscribers, NCsoft's free-to-play fantasy MMOG Guild Wars has posted impressive numbers of its own. A mere five months after the ArenaNet-developed MMOG charged into battle, NCsoft revealed it had garnered the support of 1 million combatants. In June 2006, NCsoft followed up that announcement with news that the original Guild Wars and Guild Wars Factions, the game's first stand-alone expansion, had combined to sell more than 2 million copies.

With the game's second stand-alone expansion, Guild Wars Nightfall, having arrived last October, NCsoft today announced that the trio of games in the Guild Wars series has now sold a combined 4 million units. The milestone comes on the eve of the release for Guild Wars' third update, Guild Wars: Eye of the North, which is set to go live next week on August 31.

Billed as the first true expansion for the game (and the only one that isn't a stand-alone product), the focus of Eye of the North is on adding new content for existing players rather than introducing a new chapter to the game. The new content for the game includes new dungeons, heroes, items, and story content. ArenaNet also plans to use Eye of the North as a segue into Guild Wars 2, which is slated for a 2008 release.

In anticipation of Eye of the North's release, NCsoft will be hosting a sneak-peek weekend for the latest expansion from August 24-26. Players will be able to retain any achievements earned during the trial weekend when Eye of the North officially releases. For more on the sneak-peek weekend, head over to NCsoft's official site.

Guild Wars: Eye of the North is rated T for Teen and retails for $39.99. For new players looking to join in on the action, NCsoft will be bundling the original game with Eye of the North for $59.99. For more on Eye of the North, check out GameSpot's previous coverage.