Finally got around to writing the introduction to the game. So that's done. I may still want to post an example of gameplay to give an idea of how the game, well, plays. Those are usually fun to write.
The last major part to finish (well, start if I am being honest) is the generically-named "Settings and Adventures". This is intended to be the "Game Master's Guide" section of the book. Given the expected extent, I'll probably have to add a number of subsections, varying from tips to running the game to the random adventure generators. To be truthful, I am not entirely what I am going to put in there yet.
Still, I'm pretty happy with what is up there already. The core rules are done (although it is still missing some stuff, like what to do when the players hide in a building and the zombies are battering down the doors) but the game is in a playable state. We'll see some changes based on further play-testing and editing, but the core framework is done. Whew!