Drop the marble through the holes and out of the double ring.
Swipe or tap to tip the stack; the marble rolls until something stops it.
Two fingers or a right-drag turn the view, and a pinch zooms.
Keys and phone tilt
The arrow keys or W, A, S and D tip the stack toward that side of the screen, as do the wheel and a two-finger swipe on a trackpad. Z or Backspace undoes. Ctrl and the wheel, or + and −, zoom; Q and E turn the view and 0 sets it back.
Hint shows the next tip; press it again to play it. The top line shows the board, then the moves made and par.
Phone tilt, in Settings, tips the stack as you lean the phone. Hold it comfortably for a moment, lean, and come back to level between moves.