Aragami is a third person stealth game about a ninja with shadow powers on a quest for revenge. Besides the evident fact that the player is less visible while crouching in the dark, shadow also recharge your powers while the light drains them, this is the main mechanic in the game and it works pretty well because most enemies aren't threatening at all for an Aragami with full shadow essence.
On a similar note, there are no different endings depending on how many enemies you kill, but you can still beat the game as a pacifist if you want.
I don't have much else to say, I think Aragami is a competent stealth game, albeit a little derivative. Still, the gameplay is very open ended and I don't think it's bad to take a mechanic from a different game as long as it's good. I would recommend Aragami to fans of the stealth genre and people who want to get into it since the difficulty level is generally low.