Is there even a main goal whatsoever to Rust or is it just a survival sandbox?
My main experience in witnessing said game was the hilarious Penis Brothers [NSFW] Let's Play videos. Says a little something about human society when you give way to a lawless land and the reigning outcome are big floppy penis raids.
Main goal I believe it just to survive, they removed zombies and replaced them with wild animals. Seems to be pushing people towards building a camp and stockpiling supplies and withstanding raids from other players.