I'm not sure I get this book. It is like two books glued together which kind of totally contradict each other and not quite sure what it wants to be overall.

The first half is a mildly interesting instruction manual to survive the zombie apocalypse. So, there are lots of lists of supplies (this many guns, this much water, etc). And there is some deep thinking about the realities of fighting zombies, i.e. wear tight clothes which can't be grasped, use these sorts of weapons instead of these others, etc.

It is sort of like Tolkien's Silmarillion, loads of back story to build new imagined worlds. It can be a bit tedious to wade through the lists and world building.

Then the second half becomes a completely different book. While the first half seems to imply that zombie attacks are well known and maybe a commonplace event in the world it is addressing. But the second half becomes a (imaginary) historical survey of zombie attacks (i.e. the Roman legions fighting zombies). It takes the position that only a select few know about these are there are vast cover up efforts by authorities. It kind of destroys the internal consistency of the book.

The second half does include much more actual storytelling (as opposed to lots of lists) and is probably much more interesting.