Surviving the Apocalypse, Becoming an Immortal Alone

[Sci-Fi apocalypse setting + solo cultivation protagonist, not a mindless action story] This is a fragmented world where human civilization is struggling to survive on a planet ravaged by the Blade Beast disaster. The flames of civilization flicker intermittently in underground bunkers, while human elites in space are preparing the ultimate plan to fight back against the Blade Beasts. However, the road ahead for humanity appears dim… “So,” a Master in the Great Ascension stage, who has been cultivating for 125 years but failed the tribulation and had his soul sent to this ‘strange’ world, sighs as he looks up at the sky, “What does this have to do with me?”