One theme in "The Most Dangerous Game" would be violence and cruelty:
Essentially an action-packed thriller, Richard Connell's "The Most Dangerous Game" builds around explosions of violence. The violence of his malicious host, General Zaroff, initially shocks Rainsford, but as he fights to stay alive he becomes caught up in Zaroff's game.
Likewise, another theme would be revenge:
The conclusion of "The Most Dangerous Game" inspires many questions, including: Has Rainsford become a murderer just like General Zaroff? How has he changed, and why? Although he won the game, and General Zaroff appeared ready to set him free, Rainsford still killed Zaroff. Zaroff's murder, therefore, is not self-defense, as it would have been before Rainsford won the game. It is either an act of revenge or a killing for sport.
If the latter is the case and Rainsford has changed into a man like Zaroff, one could easily conclude that man's greatest competitor is himself. Rainsford does seem to be caught up in the game. He is no longer satisfied to survive. He must kill for revenge or sport. He has begun to compete with himself. He no longer struggles to live. He now has the upper hand. And the fact that he had never had a better night's sleep is an indicator that Rainsford is competing with himself. He has something to prove to himself. He is the better, smarter man. Now that Zaroff is gone, the question is whether or not Rainsford will continue Zaroff's tradition of hunting men. Is there a battle going on inside of Rainsford?
No doubt, Zaroff competed with himself. He had succeeded at hunting animals until the hunt began to bore him. Then he began to hunt humans. He seems to be struggling within himself for satisfaction. He wants to compete with an another human who can match his wits. He is competing with himself to have power and dominion over mankind.
Now that Zaroff is no longer in the way, will Rainsford take his place is the question:
When he first learns of Zaroff's sport, Rainsford is horrified. Yet, during the game he kills the dog and Ivan and does not indicate remorse. Connell thus opens up the possibility that playing the game changes Rainsford.
Will Rainsford begin hunting humans? Will he feel that hunting humans is a way of competing with himself. Will Rainsford no longer be satisfied hunting anmals?
Will he merely replace General Zaroff? Sparing Zaroff could have brought the opportunity for authorities to prosecute Zaroff for his crimes, but Rainsford resorted to the violence he initially abhorred.
Is it more exciting competing with oneself? The idea of hunting takes on a new outlook when Rainsford kills Zaroff. The fact that he could sleep in Zaroff's bed and comment that he had never had a better night's sleep alerts the reader that Rainsford has changed. The new game is man versus man--a competion with oneself.