how important is supsense in the story?

This story is driven by suspense. Everything hinges on if Rainsford can beat Zaroff in Zaroff's twisted hunt. It is a case of the hunter becoming the hunted. This old theme is set up in the beginning of the story with the mention of "ship-trap Island" and the rising action is triggered when Rainsford falls of the boat. The suspense builds all the way to the climax which literally ends in the last sentence of the story.