I once had a project called "Color Gravity Cat", a project with an edit off the Gravity Cat default sprite. In this new version, there is also a cat drawing a rainbow line! HOW I MADE THIS: For the rainbow Gravity Cat, I added the script "set pen color to red" and "set pen size to 10" to the first "when green flag clicked" and a "change color by 1" to the forever loop in a default Gravity Cat.
