One of the best topics in "The Most Dangerous Game" is the conflict of Man vs. Man, or the struggle between two characters that defines the core of the story. Rainsford is captured by General Zaroff and made to play in his "game," the hunting of humans for sport. Rather than participate in the hunt as a hunter, Rainsford opts to be hunted as prey. The clash between Rainsford and Zaroff's hunting skills provides the suspense and the climax of the story.
Additionally, the difference between hunting for sport and hunting for necessity could be explored through Zaroff's entirely selfish actions -- he hunts only for sport, and chooses humans to provide a mental challenge -- and through Rainsford's pragmatic reactions -- he uses his hunting skills to fight back, killing because he knows he must to survive. If Rainsford played the game as Zaroff meant it to be played, he knows that he would die, so he instead chooses to alter the rules according to his knowledge of the hunt.
I suggest that a good topic for an essay about "The Most Dangerous Game" would be about how Rainsford changed as the result of his experience in being like a hunted animal. The story can only claim to be important if the viewpoint character undergoes a significant change. Rainsford is indifferent to the sufferings of the animals he hunts for sport until he realizes what they feel like when he himself is put in their position. There used to be an editorial adage that "Characters must change." A story cannot be considered significant if a viewpoint character goes through a highly emotional experience and comes out the same person he was before. That would be pulp fiction and hack writing. Rainsford may give up big-game hunting entirely. He could even become a conservationist. A good example of a viewpoint character who changes as a result of what he experiences in a story is Nick Carraway in F. Scott Fitzgerald's The Great Gatsby. In the end Nick decides to go back to the Midwest because he disapproves of what he has seen of the dissolute people in the East of the Roaring Twenties. Another good example of how a major character changes as a result of going through a number of highly emotional experiences would be Pip in Charles Dickens' Great Expectations.