Reading through it now, I really like the timeline, where the setting starts as something resembling the real world (although anyone familiar with the Gulf of Mexico can see from the map in the book that the geography is different to make it more gamable) to something like Darkest Dungeon in tone and then beyond into a Lovecraftian endgame.
One thing that looks challenging is figuring out when to set a game, since ash and the undead don't show up at all in the earliest version of the games, and based on the timeline, it looks like a fair number of monsters only show up relatively rate in the timeline.