Stealth games in which you can become "one with the shadows" cover a wide range, though I guess spectrum is the more appropriate word here. You've got sober infiltration games like Thief, which metes out gradations of light and dark with the care of somebody calculating their tax expenses, and stylised affairs such as Mark Of The Ninja, in which stepping into shadow desaturates you and sort of makes your character far too fancy for enemies to notice.
There are games such as Splinter Cell, in which hiding in shadows rests on a gentleman's agreement with NPCs not to perceive the big green torches attached to Sam Fisher's head. And then you have games like Ereban: Shadow Legacy, which has just been given a release date - 10th April. In this mystical third-person stealth-platformer, your character can literally disintegrate and travel through shadows as a ripple of dark energy - a transformation that puts me in mind less of Thief than of squid-mode in Nintendo's Splatoon.