• Hold and drag the figure to turn it right round — 360 degrees, and past, never sticking
  • Dragging turns the CAMERA, not the figure — and the options cannot be turned, so it is still mental rotation
  • Arrow keys turn it too, for anyone who cannot hold and drag
  • It never zooms as it turns — the coordinate box is the same at every angle
  • The Shepard–Metzler figures, as the textbooks pose them
  • Compared by canonical form over all 24 rotations of a cube
  • No two options are ever the same figure, so the board cannot be solved by elimination (npm run verify:rotation)
  • A wrong pick explains itself: a mirror, or a figure bent differently
  • 'Turn it for me' really does turn the figure, one step at a time
  • EQ: three misses in a row buys a breath, then the turning aid opens itself
  • Drag to turn the figure freely with a fingerplanned

✓ = done · ☐ = planned. Every game is built one step at a time like this.