The war years of the Otherworld
As a fantasy modern story that travels from an alien star to the earth, there are large military chapters and a lot of fantasy pages, reasonably distributing fantasy and reality, and telling multiple stories from the perspective of multiple characters.
There is a lot of detail at the beginning, and it gradually gets better in the middle, with the growth history of the male protagonist as the unfolding, telling the story of a generation of people who live seriously!