It's an augmented reality air guitar app that tracks your hands and plays along. You can even pick individual strings!

I don't know how well you can make it out but there's a little broom guy there with glasses, playing air guitar with his broom, and I guess this is meant to capture the spirit of the contributors.

Air Guitar Hero Muscle-based interfaces could eliminate a lot of the peripherals we use to control computers, like mice and video game controllers, instead taking commands from our gestures.