There is new gaming ide and platform called Godot which is MIT license and I found it is a great alternative to Unity3d. I would like know how I can suggest a partnership between you and the project to be a third alternative to Unreal and Unity for rapid vr app/game development.
The project just won Mozilla award so I hope Oculus could check out regarding a partnership in the future. Would be nice if Oculus could support open source projects as well too.