What game would you nominate for this honour?
Do 2.5D games count or are we talking specifically 2D? With Bloodstained being so fresh I can't help but think of it, it looks so good.
If it's strictly 2D, though, I suppose I'm going with Ori and the Blind Forest too. I'd name a couple honorable mentions, but when I start thinking of them it's too many, so, I won't.