As with all good stories, we cannot simplify answers into neat categories. Therefore, in "The Most Dangerous Game," we can say that there are many conflicts. For example, when Rainsford had to extricate himself from quicksand, he was fighting against nature. When Rainsford had to overcome feelings of disgust in playing the "game," he had conflict within. That said, the main conflict is man versus man.
When Rainsford finds himself on the island and meets general Zaroff, Zaroff has only one thought. Zaroff wants a challenge, and he sees this challenge in Rainsford. As Rainsford is on the run in the woods, he is playing against Zaroff. The stakes are high, as it is a game of life and death. At the end, Rainsford embraces what must be done and goes on the offensive. Rainsford wins and defeats Zaroff.