Rust is an indie 2013 survival video game created by Facepunch Studios, the creators of Garry's Mod. The game's inspiration comes from games such as DayZ, Minecraft, and S.T.A.L.K.E.R.: Shadow of Chernobyl.
Pro Lots of variety in ways to die
Fauna, including bears and wolves, is trying to kill you, radiation, that's ever-present, is trying to kill you, zombies, in a multitude of colors, are trying to kill you, other players on the server, equipped with guns, are most definitely trying to kill you, and you, yourself, if you don't find food, will die.
Pro Game's multiplayer nature creates psychological tension
While there's obviously potential for working together with other players towards achieving certain goals, the more likely scenario is someone trying to kill you to get your stuff. Or even worse, deceiving you in working together to achieve a particularly difficult goal only to stab you in the back when you're not needed anymore. It's easier to take stuff from someone else than gather it yourself. And since your base is a the perfect bullseye to other players, there is constant threat of griefing.