This is a simple pico-8 program that I thought I would share. The concept is simple; it's drawing circles where the center is a point on an (hidden) circle, incrementing the color each time. You can adjust the radius of the hidden circle by using left/right and the amount of circles being drawn with up/down. Since it never clears the screen, it gives really nice visuals with the trails left behind by the circles.

edit: there is now a version 1.1, which allows you to press x/o to swap whether or not screen clearing is on or not. While this looks much more boring, it allows to see how it works much better.

Some really pretty things you can get with this.

I'd suggest posting a small gif of it in motion.