Pocket Portal VR allows you to create multi-dimensional portals that integrate seamlessly with Apple's ARKit, the Vive, Rift and Gear VR. You can make puzzle games, create rooms that are bigger on the inside, make a world with two or more major dimensions to hop between, or even carry a small portal around for quick switching between worlds.
VRTK Kit is also supported with both SteamVR and Occulus SDK.