Even if you're not into gaming, you should check out "Portal" . It's thoughtful, challenging and unique as far as I know. And the moral implications of a caring for an inanimate companion cube are…well…interesting.
It's also interesting that the creators of portal have released a three-volume soundtrack which is available for free. Coupled with the visuals and game play the music reinforces the importance of sound in order to complete a compelling experience.
If you're not familiar with "Portal" check out this short film by Dan Trachtenberg. Without giving away any spoilers, it will give you some insight into the mythology of Portal.
You may also know Dan from the "Totally RAD Show" - a wonderful podcast that reviews games, movies, graphic novels and more (Revision3). I had the great pleasure of meeting the TRS team team a few years back. Great group of guys that deserve all the success coming their way.