The mode has been announced by a YouTube channel called Virtual Reality Oasis. It will be free and available only to Steam users.
Unfortunately, there are not many details right now; the only thing we know is that the mode is built over UEVR, which allows you to convert any Unreal Engine game into a VR perspective. It is not something new, we already have many other games that use similar modifications, but they usually work poorly. Let's hope it will not be the case.