I addressed this in another very similar post.
Conflict and/or Suspense.
As the writer of a story you must give your audience a reason to want to continue reading. The genre is inconsequential as each genre has its own fan base and following so if I were to write the story for a horror VN and the science fiction fans said, "that's dumb, you didn't include any laser beams or aliens." they would be missing the point. If I wrote a science fiction story without any elements of horror the inverse would apply. If, however, I wrote either without any conflict or suspense regardless of basic genre specific content, there would be no compelling reason for my audience to remain engaged in the story and I have failed in the basic principal of story writing.