What you see above is Nathan Andrews' full head- and weapon tracking mod for Half-Life 2, which he created in preparation for the release of the Oculus Rift virtual reality gaming headset. It looks insane.
The Oculus Rift, which raised millions of dollars on Kickstarter in 2012, is hopefully coming out later this year.
Half-Life 2 VR head and gun tracking mod for the Oculus Rift