Because almost all of my assets are 2D .PNGs I decided to add a bit of depth using the drop shadow tool in After Effects. I initially planned to use identical settings for each asset but sadly the parameters seemed to be based off the image size, so the same settings produced wildly different visual effects. In order to combat this I started with red red ball and just tried to match everything by eye as best as I could.
Overall I think I managed to keep things relatively homogeneous, or as close as is needed given that individual elements are only on screen for quite a short time, meaning a perfect match is not as essential. Below is a screen-shot of the effect being used on the work in progress: