Main article: Erratic Turtle Graphics
It's turtle graphics, except there's a small margin of error. You might ask for "Turn right 90 degrees" but you might get only "Turn right 89.91 degrees".
It uses a faint pen, so if you repeat the drawing instructions many times over, you get a nice pencilly noisy effect.
There is support for a rudimentary command language similar to Logo, for user-created designs. The commands are:
fd NUM move forward this many pixels rt NUM rotate right this many degrees lt NUM rotate left this many degrees setxyr NUM NUM set the coordinates, as a percentage of the width and height of the canvas shiftxyr NUM NUM adjust the coordinates, as a percentage of the width and height of the canvas seterr NUM NUM set the error rate for rotations and movements respectively shifterr NUM NUM adjust the error rate for rotations and movements respectively