A small Python 3 + pygame program that renders pixels in the complex plane, colouring them by the number of iterations of an operation it takes to escape the circle of radius 2.
Essentially, it displays a picture of the Mandelbrot set.
Python 3
pygame
Run the script, a window will pop up. It will start slowly rendering the set.
If the aspect ratio is bodged (after resizing or box-zooming), hitting the space bar will fix it.
Plus key zooms in, minus key zooms out.
Backspace key shows you the startup render.
Left clicking sets up a cursor. When you right click after the cursor is set, you will box zoom on that area.
F11 toggles fullscreen.