A number of you have had the game crash on launch as it did not support 7.1 surround sound yet. This has now been patched. It is likely you were using headphones that advertised themselves as having full 7.1 surround support, which should now work properly.
7.1 Surround Headphones Support
Build and release context
Recorded Steam release date:
Within one calendar day of this post (UTC). The listed date does not establish an exact launch time.