Before the internet, before people even really cottoned onto the idea of games magazines, publishers had to sell things the old-fashioned way: with TV ads and catalogues.
Most catalogues were simple affairs, all bright lights, screenshots and slogans, but sometimes publishers went a little left field. Like Activision did in 1984 when it basically commissioned an illustrated children's story.
With its fancy prose and Yellow Submarine-esque imagery, it's certainly a novel approach to selling video games. And hey, judging by the catalogue's strength - featuring all-time classics like Pitfall and Ghostbusters - maybe they just figured the games would sell themselves, so the creative types could go nuts.