made background, used solid blue layer, then a blue and white gradient on layer above it, the ground is made of solid brown with some dodge and burn for texture. Brick wall is made of random rectangles made with the marquee tool, fill and then added noise.
step 3 of 4
starting to fill in cat and mouse, used shading on ground and wall
step 4 of 4
added shading and highlights to the cat and mouse, finishing up some small areas.