Athanor is a French Sci-Fi RPG published in 1989.
A virus spread all over Earth. The players, like any other humans, have the power to mutate, to adapt themselves to the environment, and also have psionic abilities.
People live in isolated communities (small or big), micro-worlds, until they decide to go on a trek explore the rest of the world and parallel universes.
This is the boxed set that include the core rules and an adventure.