Prosopon
A face under a light, and the light answers to what the hands draw.

Pinch thumb and index, with either hand, and draw a line in the air. Every line is a light and a wall: it glows, it lights your face and it casts shadows, because the whole frame is lit by 2D global illumination (radiance cascades). Lines stay.
The light over your face takes the running mix of every colour drawn so far, so the face slowly turns the colour of what was drawn around it.
No camera, or no hands in view? Drag to draw instead.
WebGPU through vgpu. Hand tracking runs on MediaPipe in your browser. No frame leaves the machine.