Great concept! However my mind started already coming up with ideas how to circumvent this like printing out a color picture of grass! Hope you can detect these fake attempts! :)
If you have no intent of using the app, why install it in the first place?
But then, the purpose is less about going out and touching grass physically, and more about being aware of what you're spending your time on. A moment of self-reflection, if you will, and whether that's you going outside to find some grass or finding where you put your colour picture of grass and turning the lights on to get a good picture of it is by the by.
