HL2 VR mod available now for free.
https://youtu.be/q-08KCheaGg
"Full room-scale VR with tracked motion controls. Physically walk around, pick up objects and climb ladders the way that only Virtual Reality allows
Intuitive and realistic weapon interactions, with quick and easy weapon switching via a radial menu, ammo storage over your shoulder, functional iron-sights, two-handed weapons, and manual reloading
Control options including; full left-handed support, a laser sight, and arcade style “quick reload”
Comfort features like motion vignette and 3rd person vehicle camera. (Note: there is currently no teleport movement option)
Playable on any VR headset which is supported by SteamVR"