The thing that seems to be present in all my favorite post-apoc settings is watching [i]the very last[/i] humans doing their thing.... the numbers don't have to be super-small, but they can be. I'm thinking of everything from Battlestar Galactica (where they show you exactly how many humans are alive at the start of each episode), Attack on Titan (you're watching the last city crumble and the last people die), Demon's Souls (especially when saving one character causes him to roam the last refuge, secretly murdering the only humans left in existence), heck Interstellar even counts. That's always an intriguing thing to me. The end of the [i]world[/i], I mean.... I like the world, sure, but I care way more about the end of [i]human beings[/i]. We're easily the coolest things on the planet anyway.

That tends to get lost when you start bringing in robots and zombies and mutants and all that. It becomes about [i]killing the titans[/i] instead of [i]just friggin' existing, somehow.[/i]