This is a musical pachinko machine. It is a sequencer that allows you to compose music with a certain amount of indeterminacy or chance.
When you press the space bar, a ball is launched from the top with a random direction and velocity. You can also launch balls at the mouse position by pressing shift.
You can assign samples to the pins with the three rows of the keyboard - Q-Y for sound-set 1, A-H for sound-set 2, and Z-N for sound-set 3.
There are two versions of the program. The first one uses a built-in sound library that has four sound-sets - Casio Sk-1 drums, Rubber Bands, Glockenspiel, and Mbira. The other version uses the OPEN-SOUND-CONTROL communication protocol to trigger sounds in an external application.
Use it here
See documentation video here