Wow cheers for the detailed feedback.
I can confirm that all the art assets were made specifically for this jam. We had Oscar doing the 2D drawings and I was handling the 3D assets with my typical workflow from Blender through Substance Painter and into Unity with the occasional custom shaders.
We certainly did have some issues getting Unity's current physics engine to cooperate with what we needed to make the game fun to play. We used a few neat tricks and compromises to get it to where we thought hitting the ball around was pretty entertaining.