How hard is it to convert a non-VR game to a VR game?

Good day all,

I have a non-VR game that I have made that has a few keyboard and mouse controls (e.g. picking up objects, opening doors after pressing a key, looking around with the mouse), and I’ve been thinking of turning this into a VR game, so I wanted to know how hard it would be to actually achieve this. I’ve never worked with VR before, so I don’t really know how the controls work.

I recently got an Oculus Rift so I really want to test this out, and I couldn’t find any good suggestions on google, so I’d really appreciate any help or suggestions!

There isn’t really that big difference in the code. Mostly there is the input method that will take the longest to get right (since you need to ditch the mouse and keyboard)… And the handling of pause and some other things - especially if you intend to be on the Oculus store or even Applab.
Not sure if you now can use the Unity GUI (in a menu for example) or if you have to make your own GUI.