If you haven't heard of Auditorium, you owe it to yourself to check it out.
It's a puzzle game involving music and some physics controls that change the way a "stream" of audio is guided.
The goal is to fill all the "audio levels" on the screen, using the controls offered you. The controls have a diameter of area they offer for their influence to take effect. This diameter can be expanded and contracted, and it is up to you to experiment and discover what will work to accomplish the goal.
As the site states, "There are no right or wrong answers; there are many ways to solve every puzzle."
The game rocks; I'll probably be making a donation after the new year. Good work to the Team putting Auditorium together!