Shattered Horizon was released on Steam this week, and it is full of zero gravity gameplay and "silent running."
What silent running does is allows you to turn audio cues off, providing "a stealth advantage while sacrificing radar, HUD, and maneuverability."
Unfortunately, the $19.99 title may put some off because it requires DirectX 10, a DirectX 10 compatible video card, and Windows Vista or Windows 7 with no support for Windows XP or DirectX 9.
Time to update if so.
There's a video of it over on D'toid.