It's no secret to anybody who has even heard of this game, that Ninja Gaiden on the NES is a very tough game.

After playing it, I feel very conflicted on it.
The controls are solid, and I really like how fast-paced this game can be.

The story, while nothing too amazing, is nice to see unfold, and this was also one of the few NES games to have cutscenes, so that's also neat!

The music is really good! There are a lot of memorable tunes, and gets you excited for the action ahead.

The biggest sticking point, in my opinion, is the level design, more especifically, the enemy placement.
At first, it's rather simple and you won't really have much trouble, but the more you progress, the more punishing it gets, as the game just throws more and more enemies at you, nonstop!
And the enemies also constantly respawn, which makes matters even worse.

By the end of the game, I was just tired of all of the shit it threw at me, and combined with a final boss who throws projectiles at you that are very hard to dodge, this game drained me by the end.

It's not a bad game, but I really wish Ninja Gaiden's method of giving you a hard time wasn't by spamming enemies left and right.