Stealth, befitting of its very definition, sneaks into our games in many forms. Sometimes it slips in under the guise of a role-playing game, such as a no-kill play-through of Deus Ex: Human Revolution. In other instances, it blends with an action title, like the Sam “Panther” Fisher version of Splinter Cell Conviction. And not often enough, it comes in its purest shape, in which you face near-certain death – or at least, extremely long odds – if you’re spotted. The Thief series, quintessentially. Or, in 2012, Mark of the Ninja.