I love apps that are good for an intro or breakdown of a song. Boinkss fits that description. Draw on the screen and you will create some interesting “woman walking down a scary street at night” sounds.
“Boinkss is a sound toy that uses simulated physics to create shifting sonic patterns and freeform sequences. The player draws colourful lines and shapes, then drops bouncing balls into their creation. The collisions of the balls results in dynamic and varied sounds. The different colours in the palette relate to different sound types, which can be combined in many different ways.” – noisetoysound.org.uk
For more info: noisetoysound.org.uk/boinkss