ALfheim Online [SAO Story 2] (ALO)

«ALfheim Online» (アルヴヘイム・オンライン, Aruvuheimu onrain?, abbreviated as ALO) is a Virtual Reality Massively Multiplayer Online Role-Playing Game (VRMMORPG) in the Sword Art Online series that was released a year after the beginning of the «Sword Art Online» incident.[1] It is compatible with any FullDive device. The game features nine races of fairies, whose goal is to reach the top of the giant World Tree, in order to meet the Fairy King Oberon. It was said that Oberon would turn the first starting race to reach the top of the World Tree into the legendary race of ALFs, with the ability to fly for unlimited time, but this later proved to be a lie. Once ALO was acquired by Ymir, unlimited flight, except in dungeons, was granted to all fairy races.

It is the setting for the Fairy Dance Arc of the series as well as the setting for the Mother's Rosario and Calibur side stories, as well as Calibur's alternate ending, Calibur SS. Instead of the level system that Sword Art Online emphasized, ALfheim Online pursues skill development and encourages killing other players. This kind of system attempts to eliminate the enormous gap between new and old players that exists in level-based games.