What setting would best fit the theme of survival of the fittest?

A post-apocalyptic wasteland would best fit the theme of survival of the fittest, where resources are scarce and the environment is hostile. In this setting, characters must navigate treacherous landscapes, fend off dangerous creatures or rival factions, and adapt quickly to changing circumstances to survive. The relentless struggle for food, shelter, and safety emphasizes the brutal reality of natural selection and the strength of those who can adapt and overcome challenges. This grim backdrop highlights the primal instincts and moral dilemmas that arise when survival is at stake.