The Hex Live Wallpaper is an Android live wallpaper that draws hexagons that change colour over time; the colours, speed and size are all configurable.
I created it several years ago after finding a static blue hexagon wallpaper on the internet and deciding that an animated version of it would probably look really nice.
I was only able to create thanks to the great article on hexagon co-ordinates by Red Blob Games, it is known as the article on hexagons in programming.
The app has many predefined colour sets such as Ocean, Nature, Stormy, Royal, etc.
Recently I created a template live wallpaper project to help people make their own after I had to spend quite a bit of time finding information on how to implement live wallpapers on Android, read about it here.