Rainsford was being hunted by the murderous by General Zaroff. He ran throughout the jungle trying to seek a way off to get help but the whole island was surrounded by rocks so there was really no escaping the island.
Rainsford had to escape the general at all costs. He took off running deeper into the woods. He had to dodge tree branch after tree branch and bush after bush. The trees trunks were not thick enough to hide Rainsford so he had no where to hide. What was he going to do?
Finally, he had an idea. He ran to the closest mud pit he could find, laid down in the mud, and began to cover himself with mud. If he couldn't outrun the General, he could hide from him and wait him out. That is how he would win the game, he would use his brain instead of his athletic skills.