In the last days, there is no morality, only flesh and blood.
Betrayed in his previous life, he is no longer cowardly in this life. He is decisive in killing and no longer fantasizes about propriety, justice and shame in the apocalypse. All he has to do is to achieve his goal by any means necessary!
The end of the world + rebirth + small space + decisive killing + bloodshed + various mutations + never the Virgin
This book is heavy-handed, so if you don't like it, don't read it.
Also: Story is king!
It feels like the protagonist is a rebirth master