Greetings from ChatGPT
Oberon (Sugou Nobuyuki) was the main antagonist of Sword Art Online: Fairy Dance. After SAO was cleared, most players woke up, but Asuna didn’t—she was secretly transferred to ALfheim Online (ALO), the follow-up game, where Sugou trapped her to control her, marry her, and take over her father's company.
They are called SAO survivors because they were among the players trapped in Sword Art Online, where dying in the game meant dying in real life. They managed to survive and escape the game.
FOG is Fujino's own creation for his alternate universe.
PS: Everything is a bit more complicated than this, but I guess this answers your questions.