Here are two characters, Ahuni (the wolf) and Etum (the husky), starting up a campfire in an abandoned building, during the post-apocalyptic times.
This was quite a challenge for me. I hadn't really done clouds or cities before. I fiddled around with the brush settings on SAI until I had something that I could call a 'cloud' brush. The buildings I just used it with a wet canvas texture. The part I spent time on most though was the shading/luminosity. Took a few hours to get it to where I could be satisfied with.