While gamers love their full-on action, there's a lot to be said for that particular subset of games that adopt rather subtler, more covert tones.
What we're talking about, in an appropriately evasive way, is the stealth genre. Such sneaky games are tense, challenging, and extremely satisfying.
Or, at least, the best examples are. Take this list of the Top 5 stealth games on iPhone, each of which will sneak up on your free time and grab it in an unbreakable chokehold.