Oculus Rift Support is not yet fully built into the game. However, there is a dev post stating how to get it working experimentally and a guide[1] It is being worked on: right now it's working, but it's not great by any means. Rough instructions are here: DO AT YOUR OWN RISK!!! To increase immersion, try not to use cheats.
UPDATE: An official Guide for using the DK 2 was made available. Be aware: it is still a heavy prototype feature.
To play with Oculus Rift Support, select the "Oculus Rift" button when starting the game. This feature is currently only available in Experimental Mode.
Common issues: "When I run OVR mode, it shows on my monitor, not on my rift."
Make sure in your Windows Display Settings that the Rift is on the RIGHT side of your actual monitor, like this: http://i.imgur.com/YKGSVes.png NOT this: http://i.imgur.com/z5XAW7R.png
If you still have issues, try making sure your Rift Display Mode window looks like this: http://i.imgur.com/GVnp1Tw.png These settings aren’t strictly necessary, but they are the ones that have been tested.
About
Experience Subnautica in Ultra Wide Field of View. The Oculus Rift provides an approximately 100° field of view, stretching the virtual sea world beyond your peripheral vision. Your view of the game is no longer boxed in on a screen and is only limited by what your eyes can see. The combination of the wide field of view with head-tracking and stereoscopic 3D creates an immersive virtual reality experience.
