Shannon Galvin's Contributions
Shannon Galvin worked at Maxis starting back in 1994 and all the way up through Spore, where he did concept art and 3D modeling (remember the plants and the huts---that was him!). He's currently working as lead 3D artist on Jonathan Blow's upcoming game The Witness.

He made a full set of resources that he used to tell me a pretty great story, which you can flip through here:
Shannon vs. Jason: Are We Home?

He also packed all of this stuff up into a resource pack, which is available for free to everyone who bought download access to the game. You can use his stuff to tell your own stories, or just poke at it to figure out how he made all those subtle shading effects.

You can see more of his personal work here:

And there's more! Two tutorials: