From the introduction:
618 is a game of conspiracy, in which you investigate the true purpose of a mysterious institution.
It is set in the near future: but a "retro-future", a bleak near-future, as seen from the 1960s or 1970s.
It is a world of grey concrete buildings and automated filing cabinets; of room-sized computers and terminals glowing green; of men in thin ties and women in make-up. For inspiration, think of the TV series The Prisoner or Terry Gilliam's film Brazil.