Turn until the footprints appear. Then take a step.
Everything deciding what you see here is the guide's real code, the same trailAhead() that runs on a walk. The dial stands in for which way your body faces; on a phone, the compass button makes it the real thing: turn yourself, and the prints obey.
The drawn corridor is a stand-in for a recorded walk, a bend and a straight, like a terminal hallway. The blueprint is at /footprints-concept.