While Ninja Gaiden is absolutely grueling and it's level design (specially on it's last 2 stages) is something that 33 years later would be considered outdated and cheap, the controls being so smooth and responsive makes up for most of the flaws presented.

Funny cutscenes, catchy soundtrack and just a lot of great satisfaction all around. If you're having trouble in the latter levels, try searching some secret tech, such as cancelling your sword mid-air so you can do more attacks before you touch the ground, really helpful in the last few bosses!