Turbo mode recommended. (Shift click green flag.) I recommend setting 'Iterations:' from 70-150. A Mandelbrot Set will be displayed, click any point to begin the rendering of a Julia set. It takes the coords of the point you clicked, divides them to fit the screen, and then uses them as parameters to calculate the fractal. You will probably notice that clicking points around the edges of the Mandelbrot set come up with the coolest results.
To slow? https://turbowarp.org/#381873080 The main calculating script is from the scratch wiki. Some recommended mouse coords: 39, -1 50, 80 -104, 10 40, 67 Feel free to remix or use the scripts, just credit me or the scratch wiki.
