I made a small update to the bgs. The psychedelic ones should be tilable and would look best with a distortion wave like shader on them. BG 6 and 11 should be mappable to a cylinder.
The forest ones are static. You can make a static shader that will always billboard to the camera view and apply that to a box encapsulating your level or have it always render into the viewport as a bg.
If you are using Godot you can grab the Ultimate Retro Shader Collection from Github and use the scrolling sky scene which has fitting shaders set up. If using Unity or Unreal im sure you can easily replicate that one!




