This app was mentioned in 4 comments, with an average of 1.50 upvotes
Did you think about or even try to control jumping through doing a jumping motion (bend your knees and push up fast)? You might be able to detect it reliably through the positional tracking of the head.
I once played a Cardboard game (Wizard Academy) which had this feature in. More as a gimmick then a game mechanic.
It might turn out to be tiring, but you will get enormous quads ;)
This is already in that wizard type game made by the same people that made germ buster. Unfortunately its not always responsive and is really underwhelming
Edit: https://play.google.com/store/apps/details?id=com.realiteer.wizardacademyvrcardboard
Thanks. I actually posted the wrong Link. I wanted to post the new Game from the same developer https://play.google.com/store/apps/details?id=com.realiteer.wizardacademyvrcardboard&hl=de
Here's the link I actually wanted to post.
https://play.google.com/store/apps/details?id=com.realiteer.wizardacademyvrcardboard&hl=de