Total sales for massively multiplayer online franchise Guild Wars have exceeded six million units, according to publisher NCsoft and subsidiary ArenaNet. As the series prepares to celebrate its fourth anniversary, ArenaNet has released a major new content update, with additional in-game celebrations planned for the franchise’s official birthday on April 28th. The episodic Guild Wars series currently contains three campaigns and an expansion pack: Guild Wars, Guild Wars Factions, Guild Wars Nightfall, and Guild Wars: Eye of the North. The games have received generally positive critical acclaim since the franchise first launched in 2005. Guild Wars does not rely on a monthly subscription model. Instead, NCsoft and ArenaNet released the full-priced standalone campaigns six months apart, which generated sales from new players and old players. The Eye of the North expansion is the only installment that requires the player own one of the three campaigns. “We are humbled by how gamers have responded to Guild Wars over the past four years, and we are proud that the game and its community have helped to continually shape, define, and expand the genre,” said ArenaNet studio head Mike O’Brien. “Our subscription-free business model has proven to be a big hit with gamers, bringing an enormous and diverse online community to the game,” he added. NCsoft recently announced that Guild Wars, along with other titles such as City of Heroes and Lineage, would be made available via Valve’s Steam download service.