I have been following the development of Storyboard VR by Artefact, which they just released to the masses, it looks like it could have a lot of potential; Storyboard VR | Download a free tool to prototype VR ideas | Artefact I’m on a Mac at the moment, so can’t run the software, but would love to know if anyone else has had a play?
As per a lot of the previous posts… Unity looks like the other most obvious route.
Right… off to find a machine that runs Windows…! 