For the rolling sound I had 2 curves that adjusted its volume an pitch. I also fade-in the sound based on how long the player has been on the ground in order to avoid weird "popping" behaviour. I also added a slight reverb to make the sound end less abrubtly when leaving the ground.
For the shaders, I assume you're talking about the filter that's applied on everything. I made a video about it.
Thanks for playing! I have no intention in updating this game.