Runaway hello world for OO design and Java development, predesessor of GroundForge and inkscape-bobbinlace. Successors are listed on DiBL, they have different approaches.
The main program shows a working diagram in various ways: pair diagram, thread diagram, descriptive instructions or export images for animations or slide shows. It works more or less like a route planner (or a voodoo board): Walk through the instructions (with arrow keys or mouse) to highlight the corresponding section in the diagram, or click the diagram to read the corresponding instruction. You can choose your detail level in the instructions: cross by twist, stitches or higher.