I mostly lurk here but I thought I'd make a post to let you know that I've just released a patch for Pinball Arcade that adds VR support. I call it Pinball VRcade.
Pinball VRcade supports Oculus Rift DK2 positional tracking so that you can actually walk around the cabinet, lean over to examine the back playfield, and look up to watch things on the DMD. It's almost like being at a real table.
The patch works by hooking the graphics calls made by Pinball Arcade and inserting extra operations to take control of the camera and enable stereo support. The patch doesn't contain any code from Pinball Arcade itself - it simply intercepts graphics calls and retranslates them to a stereo render, similar to products like vorpx, but specifically tuned for Pinball Arcade. I've released the source code into the public domain, so feel free to hack on it!