I've been playing around with the new game, Sleep is Death. It's a two-player storytelling game, and it's pretty interesting. Check it out if you haven't seen it, it's at http://sleepisdeath.net/
If you click on the picture, it'll go to a story I made for the creator of the game, Jason Rohrer. Oh, and I did all the art in the story. Here's a screenshot:
Anyway, I decided to write a tutorial for the art I did, and here's the link to it:
Worldbuilding 101 for Sleep is Death
It's only up to Chapter 2, but I think it's coming along well.