

Fifteen students at DuPaul University's College of Computer and Digital Media have finished a project for the Independent Games Festival competition. I'm a bit surprised this hasn't* been done before:What if you saw the world with your ears? Devil's Tuning Fork is a first-person exploration/puzzle game in which the player must navigate an unknown world using visual sound waves. Inspired by M.C. Escher's classic optical illusion and the echolocation of dolphins, The Devil's Tuning Fork allows the player to explore a new mode of perception through sound visualization.
In addition to a cool concept, it's got backstory:As a mysterious epidemic causes children everywhere to fall into comas, one child wakes up in an alternate reality. It is up to this child, the player, to determine the cause of the epidemic and save the other children trapped here. By way of the devil's tuning fork, a magical instrument that allows the player to perceive sound waves, the player must find all the children and successfully escape this alternate reality, thereby waking up from the coma.
You can get it here.
(Thanks Horrible Oscar!)
* that I know of