Should you buy this game? If you are looking for a "game", then no. The Story of a World isn't a game in that sense, you are not gonna find a lot of interaction, or deep, evolving strategies. It is more of an experience. There are things to discover and to unlock, yes, but the primary point of this app is to create a meditative experience. You will have to be willing to let your mind relax, to think, to create your own understanding of what is happening if you are going to enjoy it.
"The Story of a World isn’t a game based on trying to appeal to gamers the way modern developers do. There’s no unlockables, or “levels” per say, instead, The Story of a World is more of an experience that you can choose to keep coming back to whenever you’d like. In the end, The Story of a World isn’t going to be for everyone. If you appreciate art, and are even more excited about interactivity within it, then The Story of a World may be for you" - Indiegamemag
The Story of a World is an interactive piece of art. You are presented with an empty world where you choose what happens to it.
Depending on what you choose to add to the world, be it mountains, water, lifeforms or other, the world might evolve into something new. Explore the different ways to built the world in order to find the 18 goals.