Dramasystem?
ansorca
Humams are also an invasive species out of its original ecological niche. They were supposed to stay in Africa with the hyenas, cocodriles and lions keeping them in check.
Everyday is exactly the same
Who the fuck believes anything Maussan says?
Flatpack: Fix the Future is the first game in the smash Hyperoptimistic Postapocalyptic genre of gaming. Flatpack is a game about building a new society using pre-apocalypse technology that you don't always trust or understand, and solving terrible problems creatively.
Maybe a modified twilight 2000 or Mutant Year Zero? It depends on how grim or heroic he wants the game to be.
My guess is he wants a steampunk setting with survival and base building mechanics.
Hyperborea if you like a AD&D style game.
Worlds without Number is similar, slightly more modern system.
The out of print modiphius 2d20 Conan could also interest you.
Wicked ones
Hillfolk/Dramasystem and Cortex in it's Drama implementation are the best I know of for heavy social games.
The Tiny d6 system has several ruleset for different genres and it's pretty easy to pick up.
pi equals 10