If you haven't already, may I suggest you look on this site at the Name That Plant forum and the one/s for weeds and pests.

Those who post answers there are already game-engaged.

Having a tool that enables quick and accurate identification of mystery plants seems to be associated with a certain sort of mindset. I'm personally not sure whether this can be passed on to the general public.

If I had one - it would have to be robust, water and dirt proof, solar powered, and linked to databases that range from the sub alpine to the tropics (please look at the zones part of the user ID to see what I mean).

The databases would need to span indigenous flora, pest plants for the area, exotic introductions. (Or useful subsets, initially.) Various online sites already have the foundations for this - here, with Hortiplex, Dave's Garden, Floridata, Pacific Bulb Society etc.

If this is a serious tool, then make it for serious users - including those perennial pests - botanists, who are forever changing perfectly good species names(!), growers and breeders, plus the nice folk at Bio-security and parks & reserves rangers and volunteers, and botanical gardens such as Kew.

If you want to make a 'fun' toy for a small segment of possible users then that's a very different marketing exercise.