All twenty-seven of the app's worlds. Every shape you can name was placed by hand on a locked palette. The weather is simulated, the light comes from the weather, the painting is also the collision mask — and a finished task is the full card, ended the way that world ends it, with the app's own mechanics. Drag anywhere. The finger has momentum, and every world takes it: matter is pushed, gas swirls, water sloshes, wax stretches, loose pieces are batted away.
Three layers. The painting, which is also what the weather collides with. Authored things that move — clouds, a car, a lighthouse beam, the swell — drawn fresh every frame and solid only when they should be. And the weather itself, which is the only thing simulated: it lands on the painting, it lights the painting, and a finished task falls into it.