man, i have been fighting over the last 3 hours to get half life 2 working with vorpx.
i finally got it working selecting “previous public build” hl 2 in steam half life 2 option.
what i think was messing things up is the badly implemented official VR halflife 2 mod from steam, it doesnt work at all with vorpx, and even if you disable it it still launch side by side (but without any S3D) on regular monitor with various graphical glitches and nothing in headset or not much).
i hope that will help you guys.
now it’s working great in glorious direct VR :D