Shapes can be flung (vertical is easier with the launcher trying to move), destroyed with a tap, and there's even a four-tap secret armageddon code to destroy them all.
Super configurable: shape count, size range, speed range, spin range, elasticity, tendency to flash, triangle chance, etc.
To configure: long-press on launcher background, select Live Wallpaper, browse to Big Alpha Shapes, select it, etc.
Config tip: if you run Big Alpha Shapes as an application from your regular Apps menu, then any config changes you apply will be picked up by the live wallpaper currently running! Save yourself the long press to re-apply live wallpaper every time.