See demo Follow these steps to use Shadows2D in your scene:

1. Make sure you have a floor layer - this will be the shadowed-background layer.
2. Make sure that items that should be shadowed are placed in the floor layer.
3. Make sure the main camera excludes the floor layer - your background will now become invisible
4. Create a new camera (RenderTextureCamera)

• Call it RenderTextureCamera
• Parent it to the main camera
• Make sure it's on the same z as the main camera - so it doesn't end up behind level
• Remove the AudioListener
• Remove the GUI Layer
• Remove the Flare Layer

5. Add the Shadow 2D Setup component to one game object in your scene.

• Hook in the main camera
• Hook in the render texture camera
• Select the ambient material (called Shadow2D Ambient)
• Select the light material (called Shadow2D Light)

6. Create the ambient object

• Add a new empty game object (locate it at 0,0,0)
• Add the script "Shadow 2D Ambient"
• In the MeshRenderer, set the material to the ambient material (called Shadow2D Ambient)

7. Make sure your foreground items have colliders - that's what'll be used for shadows.
8. Add a light

• Create new empty game object
• Add the script "Shadow 2D Light"
• In the MeshRenderer, set the material to the light material (called Shadow2D Light)

And you should be done!