If a writer wants to engage the reader there’s a few things he, or she has to do.  First you have to immerse the reader in the story.  Have them visualize the story as it unfolds.  Let them smell the cooking cabbage in a tenament, see the protagonist as he moves through the story.  You have to reveal the protagonist and antagonist gradually.  In a short form you might have to move it right along but in a novel you have the time and space to let the reader get to know your characters.  Let the revelations play out over time, just like in real life.  The reader should follow the characters as they go from scene to scene.  Look at serial comic strips, they leave the reader hanging at the last frame.  The reader has to wait for the next day’s strip.  The ideal story has the reader loathe to put the story down and when they do there is a rush to come back to a place they feel good.  The last thing a writer should do is at the end of the story leave the reader asking “What happens next?”.  After you’ve tied up the loose ends in this story the reader should want to follow the protagonist into the sunset.