The Evolving World: Catalyst Wake

Only 3000 humans remain after three apocalyptic events, referred to as the "Catalysts", severely decreased the population. Catalyst One resulted in the air being toxic to breathe, so everyone wears masks. After the collapse of the government, various organizations have formed, and fight each other for territory and resources. Oliver Naut is a scrappy kid who has grown up alone in the Deadzones — the most toxic areas on the planet — with nothing but the robotic swords in his arms for protection. But now he's teamed up with Namo, a skilled ex-assassin, to prevent an army of robotic soldiers fro(Storyline via IGDB)