See Death in Dust

Chen Nian thought this was a backward pastoral era. Until I see their memories. Starfleet, burning cities and gray skies. It turns out that there was a war here, the surface was destroyed, and civilization hid underground. The people living on the earth are all abandoned people - old people waiting to die, and young people who cannot afford treatment. Until one day he discovered The truth underground was more complicated than he imagined. And this war is far from over.