Although not specifically related to mobile games, I am very interested in the opportunities for wearable technology; something that no doubt will be become more relevant with new moves from Google and Apple over the coming months.
I occasionally even find time to write on the subject.
My personal view is that while such technology could be interesting for mobile games, its main significance will be in the area of fitness and personal health.
Nevertheless, combining the two worlds, I wore a Narrative Clip during Pocket Gamer Connects Helsinki 2014.
Narrative Clip is a small clip-on camera that takes a photo every 30 seconds.
It's very much a work-in-progress, and I wouldn't recommend it unless you are very interested in this area, as it's relatively expensive ($229 excluding tax), relatively clumsy to use, and the photos aren't great either.
Despite all that, it does provide a narrative for your activity; something I've demonstrated picking out 10 photos from the thousands that it took during the two days of Pocket Gamer Connects Helsinki (obv. most of them are of the floor, the ceiling or someone's tummy).
So could you make a game out of this?
Of course. Perhaps detecting how many faces I'd 'seen' a day, maybe using those faces in a game, not to mention combining this with activity or location data (synced to your phone, Narrative Clip does do location, but not fitness tracking).
More likely, the camera could check up on how much you're eating.
Either way, the future is watching...