Ninja Gaiden's world draws you right in from the start. The control is strange but the presentation makes you want to cope with it regardless.
The key to its appeal is in part the awkwardness. The game makes ninjas seem like something other than cold blooded assassins. Instead they are portrayed as light armor, mobile samurai. And they behave strangely, too, relying on magic and a very characteristic animation.
The game doesn't have a lot to work with, but it rivets attention by posing obstacles that require ample consideration to surmount. This distracts from the tile repetition. With few exceptions the game uses only one graphic for any given concept, but the sheer number of tiles, carefully arranged to create an appearance of realistic architecture, distracts from their invariance. Also important is that tiles are very rarely reused from one level to another, meaning the player doesn't have much opportunity to notice the "staleness" of the game world. The game also regenerates monsters constantly, so there is no time to give the graphics any serious consideration.
The Turbo Graphics 16 version is a whole other beast. It makes a point of using "clean" and "damaged" tiles to portray a world with apparent history, which sucks you in immediately. The immersion is deep enough that even were the gameplay poor, you might remember it just for the aesthetic value.
The difference between experiences between the two versions appears to be this: NES Ninja Gaiden draws you into the experience of being a heroic ninja, where TG-16 Ninja Gaiden draws you into both the ninja experience and a parallel aesthetic experience.
