Earlier this year, ArenaNet unveiled its plans to start producing new stand-alone campaigns for its Guild Wars massively multiplayer online role-playing game on a semiannual basis. With the second campaign, Guild Wars Factions, releasing in April, that would put the third campaign on shelves by the end of the year.

It appears the developer is making progress toward that goal, as ArenaNet today announced that the newly named Guild Wars Nightfall has begun beta testing. On top of that, Guild Wars players around the world can get a peek at the new game with the Guild Wars Nightfall player-versus-player weekend preview event July 28 to 31. Participants will be able to use the four-day stretch to try out new arenas and two professions being introduced in Nightfall: the holy warrior, dervish, and the guardian angel, paragon.

Guild Wars carries no subscription fee, and each expansion can be played on its own without the original game. For more information on Nightfall, check out GameSpot's exclusive preview of the game.