These stairs climb forever and still come back to where they started. Seen along the (1,1,1) direction, a rise of one lap and the drift across the plan cancel each other out on screen, so every lap lands on the same spot.
The panel names at the top right open the stairs, motion, and color panels. Stairs sets how many steps one lap climbs, how long the two returning flights are, how thick each block is, and how much of the screen the figure fills. Motion sets the walkers, the speed, and whether it runs. Color sets the tread, the right face, the left face, the outline, the walkers, and the ground.
Drag the stage to move the figure and use the wheel to zoom; the field at the bottom right takes a zoom value too. Double-click a panel title to switch how the panels are laid out. In the movable layout you drag panels wherever you like and keep several open at once; in the fixed layout a single panel sits in the top right.