Try starting the game from outside Steam, this should get you an actual error message.
If the error message contains any reference to OpenAL, navigate to the _CommonRedist\OpenAL\2.0.7.0\ sub-directory of the game and install OpenAL using oalinst.exe there – this should happen automatically as you first launch the game, but it often doesn’t due to a bug with Steam outside of our control. If this doesn’t help, download this and place it in the game’s win32 directory.
If the error message you get does not contain any reference to OpenAL, let me know what it says.
