FGT is an acronym for Focus Test Group. This is a pre-beta phase in which Bluehole has sent invites out to random people — much like an open beta. FGT participants do not test content like a normal beta tester, though, but rather give their opinions on the already-developed content through surveys and questionnaires.
In order to participate on FGT, you must be 18+ years old so you can legal sign a contract known as NDA (A non-disclosure agreement) or confidential disclosure agreement (CDA).Being a FGT participant prevents you to share sensitive and/or game and gameplay info. Yesterday, the TERA team took to the official forums to answer some questions about how the upcoming FGT2 will work.
Within the Q&A, En Masse has affirmed that the FGT is not meant to be a traditional beta test for reporting bug fixes, but more a study on what players think of certain aspects of the game. The game will only be available for play at certain hours of the day and will not be up 24-7 during FGT2, though it will last around a week.