This is a test scene created in Unity. It is using HTC’s Stereo Renderer to create portals. It is created for the HTC Vive, but would also work on an Oculus.
In this test scene I have created four platforms. Each is a different color. Each has one shape. On each of the platforms there are three walls. They look through to their corresponding wall on each of the other platforms. When you stand in the center of a room, you can turn your head around and see all four shapes.