First of all I would like to congratulate you for the book. I really enjoy the way you choose to teach by example letting the reader experiment with the code before getting to all the intricacies of it. It is a great approach and I am learning a lot.
The reason I am writing this thread is in regards of the unfinished chapter 11 of the beta version. I imagine that you probably already know how to continue it and this is not going to be the first suggestion you got. Nonetheless, I would like to share it with you.
Since the part where we make our character walk through the forest I started to remember the first 3D games I ever played. The one that pop first into my mind was “Megaman Legends” for the PS1. I loved that game. It was mostly an action games but it also had a lot of exploration. There were many ruins scattered which you could visit to find new parts and crafts to build and improve your weapons.
I think that a great way to continue with this example is to have the character move around the forest trying to find a chest containing some kind of treasure. At first the chest could be easily spotted but then we could hide it, so the hero needs to move around to find it. We could show the treasure when he finds it (“Legend of Zelda” style), etc.
Well, that is it. I will continue with my reading now. Thanks again for the great work!