A gift for a friend of DA

This is my 3rd advance background attempt but this time I separated two backgrounds to show the at the same time.
One side is Arrow in the post apocalyptic San Fransico from Black Rock Shooter The Game and the other side is Dead Master's domain from the Black Rock Shooter OVA

Okay to starters I kinda attempted at cell shading this picture but I kinda overstepped on this cell shaded a advance background. I need a little more practice on cell shading small backgrounds before I tackle something like this. But you have to give me points for trying at least ^^;