Games : Half Life 2 in Linux on Oculus Rift

I'm trying to play Half Life 2 and Team Fortress 2 in Linux on the Oculus Rift.

I have an ORv1. OS is Debian Jessie. Video card is Geforce GTX 460 SE. Drivers are 331.49.

I can play HL2 without issue in the normal way, 3d acceleration and everything, it runs really well.

OR shows up in nvidia-settings utility without issue. I can extend my desktop onto the OR, or make my main display and the OR overlap. Not sure how I should set things up for HL2 to detect the OR properly, but generally what I have tried to do is have my main desktop be 1920x1080, then have the Oculus Rift set directly to the right, with resolution set to 1280x800. Then when HL2 has launched, I set the video output to fullscreen, monitor 1. (rather than monitor 0, which is my normal desktop) But, I have also tried making my normal monitor and the rift overlap. No luck either way.

I launch HL2 with -vr as required. There is a button "activate virtual reality". When I click it, I get the following errors:

Unable to initialize HMD tracker. Error code 108
Unable to get VRMode adapter from OpenVR

The "virtual reality" option in the video settings is grayed out, but fixed on "enabled".

I have googled these a bit but have found nothing. The only thing I can think of is that there is no vendor or device name string when doing lsusb, perhaps this is causing some sort of issue:

Bus 001 Device 007: ID 2833:0001

Any help would be greatly appreciated!

Thank you!