Rust's world is harsh. The environment is not kind. Bears and wolves will chase and kill you. Falling from a height will kill you. Being exposed to radiation for an extended period will kill you. Starving will kill you. Being cold will kill you. Other players can find you, kill you, and take your stuff. Fortunately for you, you can kill others and take their stuff. Or maybe you can make friends and help each other survive, using the game's building tools to create a safe haven.