Im currently working on a project like this
https://bitcointalk.org/index.php?topic=5203331.msg58917761#msg58917761It use the unity engine to support a maximum of different hardware and also some Web client. Its still heavily work in progress though
Im also big fan of vr, the controllers with 6 degree of freedom clearly improve the experience of interacting in a 3d environnement, especially compared to let say an android Phone who hasnt even any buttons at all. Especially if it has good physics etc connecting the 3d world with physical motion throught touch controller is really a whole different exeprience than using a single 2 axis mouse or touch screen on smart Phone.
The headset could be less usefull, but if you want two hands + look direction vr equipement is a must
But i still try to work unity input system at its maximum to support for all kind of input control android with screen touch / computer mouse + keyboard and vr headset, plus some web interface.