the 3DS includes a built-in pedometer that tracks how much you walk, recording the data in its Activity Log program. Of course, Nintendo puts a twist on this stay-fit concept by rewarding pedestrians with “Game Coins”, which are used unlock content in games. Think of it as Achievement Points you earn simply by doing some real-world walking, which can later be spent on new weapons, or items, or anything else you can imagine.
Once again, Nintendo shows how they've been around for so long.
That pure creativity that they whip up is absolute genius.