Phew. So many shooters out at the moment, or games set in the apocalypse, or that just involve killing things. What we need is to relax for a moment and just grow a tree.
Bohm, an indie game "coming soon", lets you control the growth of a tree. And that's it! The player can "generate and control the growth of the tree in real time", and while you do that, the music adapts and changes to suit your actions.