Use Turbo Mode! (Hold down <Shift> key and click Green Flag). What is an Apollonian Gasket? Starting with some circles drawn inside a circle (eg. 3 circles here) draw the largest possible circles in the remaining spaces, then draw the largest possible circles in the new remaining spaces, etc. etc. More technically, draw circles that are tangential to three of the existing circles. There are different techniques to draw Apollonian Gaskets. - You can calculate and draw the mutually tangent circles. - You can construct it as an IFS (Iterated function system) or IFS Fractal which is the technique used here.