Every tap drops a stone. Concentric rings spread from the point, and where two or more live ripples overlap their crests and troughs add and cancel into a shifting interference lattice. The summed height field is shaded as a water surface — finite-difference normals throw specular glints off the crests while the troughs refract into shadow. Up to eight ripples live at once, the oldest recycled as new taps land. Left alone the pool keeps a composed rain: drops fall on a deliberate rhythm with pauses, and a real press over the tile takes over instantly.