Hello offby1 and welcome to the forum: as I've posted multiple times on the Kickstarter comments section (it's actually the last comment there) :
@People without game keys: there have been multiple Kickstarter updates since Book 1 has been released in October that clearly point you to where your game keys -and other digital rewards- are to be found but no "here is your key" e-mail was sent to anyone.
Short story: your game key is "waiting" for you at your Humble store account - even if you don't have one yet! (one is created for you automatically)
Long story: READ THIS thread in the forum:
The first few things mentioned there is how to get access to your key. It shouldn't be too complicated. If you still have trouble figuring out what to do feel free to ask around at the forum, everybody there is very friendly and helpful!