A point-and-click adventure that is not a direct adaptation of the Ridley Scott's film. Instead, it's a "sidequel", telling an original story, which runs parallel to the film's plot, occasionally intersecting with it. (wikipedia.org)
I'd call this point and click masterpiece exquisite in pretty much every way. So, obviously, it is not only essential for fans of the film, but also very much so for anybody with an interest in adventure games.