Floating islands, trees, water, elephants. Put them all together and you have the wonderfully relaxing Kabloom.
You play an elephant who awakes in a fairly desolate world, with a dying tree.
Water the tree, by sucking up raindrops and spraying the tree, and the world begins to transform. Seeds fall after a while, and you can plant them wherever you like, and nurture them to maturity.
It's a sandbox environment, and you can explore as much or as little as you like. The game ends when you collect six fruit, at which point the camera pans back to show you the tree filled world you've created.
Control is via mouse and keyboard, and really simple. The graphics are pretty, but won't strain your PC too much, and the sound adds a lot of atmosphere to the whole experience.
A nice thing about Kabloom is that it can be as long or short as you like, as you don't have to collect fruit at all, just concentrate on creating a forest of trees.
This is an independently developed game, and it's free! There are some drawbacks, however. There are occasional crashes, and there doesn't seem to be a save game option, so if you exit to the main menu, you lose your gardening creation!