Choose an instrument with S D F G H J K and L, then click somewhere on the screen to place a "keyframe". Space to start/stop the slider for playing. Only the sinus ("S") can have high/low pitch, the drums ones don't. I won't make a mobile version of this, unless you want to use a bluetooth keyboard to choose the instrument.
Inspired from an android app I use to make songs called "Rolling Tones". It's from where I got the samples sounds as well to make this project.
