Words that describe both men: Competitive. Skilled. Merciless. Sophisticated. Cultured. Self-Aware. 

Rainsford is also famous, respected, renowned, etc. 

Zaroff is hardened, tyrannical, wealthy, amoral, etc. 

Both men have quite a bit in common. This idea is emphasized by the way the story ends, with Rainsford essentially taking the place of Zaroff. 

For Rainsford:

Determination. Decision. Fear. Self-doubt. Strength. Character. Resolve.

Rainsford is challenged to alter his thinking, and he might have died if he were not determined to succeed. He cannot stand the idea of hunting humans, but he is willing to kill if he must to survive.

For Zaroff:

Anger. Power. Boredom. Muscle. Lust. Arrogance. Amusement. Entrapment.

Zaroff builds his hunting sanctuary because of the boredom he feels in hunting animals. His belief in his own superiority is his ultimate downfall.

I would add the words "reason," "jaguar," "prey," and maybe some of the trap names which Rainsford uses. The trap names would be a cool idea given there are surely visual images you could create to go along with them.

In "The Most Dangerous Game," some of the words or phrases that come to mind are weird, strange, evil. Others are extremely interesting, possibly exaggeration and/or hideous. This story is extremely interesting for its hideous plot. There is something evil about hunting humans. One has to realize this is possibly one of the greatest of exaggerations. While it is only a story, a first time reading it is absolutely captivating. In all its weirdness, this story keeps the reader on edge with great suspense. It is suspenseful. The first time reader cannot put the story down.

I think that to describe Rainsford during the hunt you need the word "ingenuity."  As an overall summary of the story, I might write "How you would feel if you were the prey in a hunt?"  Or maybe (regarding Zaroff) "Would you like to hunt and kill human beings?"

I might include:

Zarroff has his own island and thinks he can do what he wants. Rainsford thinks animals cannot feel, and gets to see for himself when he is hunted. Hunting human beings.  Depravity.  Insanity.  Fear.  The thrill of the hunt. Irony. Unusual victory.