Prune is a game so simple that its elegance becomes hard to describe. It's a game about trees stretching their limbs slowly toward the light, and how sometimes you must trim parts for the betterment of the whole.
Designer Joel McDonald describes it as "digital bonsai": With a swipe of your finger, you plant a procedurally-generated tree, which gracefully begins growing and branching; when it reaches light, then flowers blossom. Along the growth arc you can swipe to wick away lesser branches for the betterment of the whole, or to affect the shape of the tree.
On a mechanical level you want the tree to make enough flowers to quantify "success" (tiny stars in the sky resonate with each petal), but often this objective develops only a secondary importance. You are doing thoughtful aesthetic work, too: Pruning away some branches means a healthier, taller tree, but you can also create graceful silhouettes. Sometimes you are merely playing with nature to see what develops; you can zoom in to flick away even the tiniest twig, to rustle a little petal.
As you progress through Prune you'll gently consider environmental factors like wind, or great looming shadows against which your tree can't thrive. It's very soothing, thanks in part to the gentle ambient soundtrack by Kyle Preston.