Snowball

only what is smaller than you will stick. so grow.

a snowball on a field of scattered things: only what is smaller than you sticks, and every stick makes you bigger

A snowball picks up whatever is smaller than it, and everything it picks up makes it bigger, so the next size up becomes takeable. That is a positive feedback loop: the rate of growth depends on how much has already grown. Here the field holds things from a pebble to a fir tree, and a thing over the line stops the ball dead until the ball has grown past it. The moment a thing that refused you stops refusing is the whole idea, felt through the thumb before it is understood; by the end the ball is wider than the card and the field is bare. The rule is the one Katamari Damacy is built on; the Prince, the King and the cousins were never the point.

Concepts: scaling, feedback-loops.

An interactive you play with one thumb, on Wundr.