Thomas Jeppeson's Gravity is a "puzzle game and ambient music generator":
Use the touch screen and the two gravity fields (yellow suns - the sun in the center is stationary) to navigate your "space mic" (green planet) around. Hit the red planet to uncover sound sources in the ambient nebular
Gravity is built on the interactive music platform RjDj, which is a free download.
Links:
James Lewin
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Older Music Machines & the People Who Still Use Them
Developments for Korg's instrument have been slow but promising.