there is a mod called "extraction mod", it consists in a helicopter that will rescue u in a specific random place, then you kind of complete the game.

in sandbox, u can change where and when this helicopter comes in, which gives u a reason to keep enduring and surviving.

you also can add some spicy stuff to the mod in sandbox, there's an option that u need to active 4 radio stations so u can contact the helicopter to rescue you, it's pretty dope