While I cannot consider this App, WURM, an art application, I have found it fascinating. The description I read is.....
"Wurm is a dynamic drawing engine that turns your screen into a mesmerizing canvas of swirling patterns and colors."
There are many patterns to choose from and you can choose multiple patterns often by mistake. Each pattern also has shape behavior. It can be opaque or translucent, be outlined or solid and combined with other patterns.
The choice of colors range from groups of colors with hundreds of sets available. I could not possibly try each combination.
You may also change the background color or use your uncolored screen. I could find very few instructions but many arrows and iconic shapes to just click and try.
Moving your finger or stylus across your screen causes the patterns to change with the speed of your movement. Size, also changes as you keep your finger moving.
When I first tried Wurm it was a bit simpler. It has since, been Updated, and there seem to be many more variations. Although this App is not meant as an art tool it is surprising, just to play with it and see the magic that unfolds.