The Khronos Group, the stewards of various open protocols like OpenGL, Vulkan, OpenXR and more just revealed a new tool for XR (VR / AR) developers.
What is OpenXR exactly? As The Khronos Group explain: "OpenXR is a royalty-free, open standard that provides a common set of APIs for developing XR applications that run across a wide range of AR and VR devices. This reduces the time and cost required for developers to adapt solutions to individual XR platforms while also creating a larger market of easily supported applications for device manufacturers that adopt OpenXR".
So it's the open standard for VR games to be built with, to sum it up easily for you. It's what Valve actually focus on nowadays for SteamVR.