The so called "indiscrete" gaming is pervasive gaming. We have the tech to do it now, we had it for years in fact and it only produced one-shot gimmicks.
Let's start with the PocketStation and the Dreamcast VMU. A memory card that acts like a tiny portable console that you could use to play minigames that affects the main game. Maybe it had some success in Japan but no one I know really used it.
The DS has wireless features that allows limited interaction with the real world, and the 3DS improved on this and can count steps and do augmented reality too. Yet most players don't use it much differently from an overpowered oldschool gameboy.
Now we have smartphones with an impressive array of sensors and connectivity. But how many PC or console games take advantage of this to extend the gaming experience ouside of your room? Some of them do, and no one seem to care.
Linking games to your fridge or your car will certainly produce interesting gimmicks that will be fun for a short time because of the novelty but I really don't think it will change our approach to gaming.
What we may see more often in the future as technology advances are games you can bring with you. You play at home on you big screen TV than switch to your smartphone as you take the train (oh, sorry, hyperloop, that's the future right), then to your laptop in your hotel room. Just like movies, you can watch one on your phone and in a theater and it will still be the same movie.