Board Thread:Questions and Answers/@comment-69.9.232.197-20151202204528/@comment-25156228-20151202223238

The second arc isn't in GGO, in fact, is in ALO(the most part of it) and is called Fairy Dance, the third is "in" GGO, the Phantom Bullet Arc, fourth main arc still not adapted to anime, is the Acilization arc, it takes place "in" Underworld. (please read the articles about the arcs)

edit: the full name of the GGO game is Gun Gale Online, not Gungal Online.