When you think about it, your pallet is only a few simple rectangles that you Push/Pulled into box shapes. The realism is provided by the texture you created. This is how it should be. Complex geometry doesn't sit well with gaming because of the strain it puts on the gaming engine and your computer processor. Textures are a "low overhead" way of adding realism.

You're now going to experience just how powerful this method is, by adding subtle shadows and shading with a single click of your mouse.