Lego frequently comes out with various themed sets with science fiction or fantasy themes, often with a back story. An example would be the Mars Mission sets.
As per the Brickipedia page:
The theme focuses on the adventures of a team of Astronauts as they land on Mars and are forced to contend with a dangerous alien race.
I was wondering whether these would be considered to be on-topic for this site. Note I'm specifically asking about the story behind these series of Lego sets, not about the Lego sets themselves.