Prune is a game about planting trees, and I'm sure you think that sounds super-duper boring, but it's really not. With a swipe you can plant a tree and watch it grow toward the light. Only with your careful pruning can it grow large enough to sprout flowers and unlock the next botanical challenge.
Each level has shady areas, shafts of light, and obstacles that will knock branches from your tree. To progress to the next level, you simply have to grow enough flowers on the small branches of your tree. That means clipping off bits that won't do you any good, but waste resources all the same. It's a very natural process that you'll understand almost immediately.
Prune has very simple graphics, but it's beautifully made and the soundtrack is great. It's $3.99, but there are no in-app purchases and it has Play Games progress sync.