Ninja Gaiden. What can I say about Ninja Gaiden on the NES? The original NG in the arcades (also available on the Virtual Console) was a beat-em-up in the same vein as Final Fight, in which you played as Ryu Hayabusa, a ninja with an arsenal of three different moves and who could only use his sword for a limited time after grabbing a power-up. Awesome, right?
Tecmo didn't seem to think so either. And so when it came time to bring the game to the NES, which had no hope of ever running a decent post, Tecmo decided to instead make a completely new original game, an action platformer instead of a brawler. The game has a strange resemblance to Castlevania: close range weapon, sub-weapons activated by holding up when attacking, having to hit candles or lanterns to find these weapons and ammunition... even the HUD bears a resemblance. But Ninja Gaiden is a much faster-paced game, and its hero is much more agile: he can run, change direction mid-jump, grab on walls and, if you are dexterous enough, climb them.
The game has a reputation for being balls-hard. The "problem" here is that as agile as Ryu is, the enemies are not limited to close-range weapons and some of them, such as birds and bats, are even faster than the hero. Plus, they respawn immediately should you backtrack even a millimeter when you kill them. But victory is nonetheless possible, if only by memorizing the levels as you get pushed into the omnipresent bottomless pits over and over again.
Oh, I almost forgot: the story in this old NES game is actually worth talking about. Ryu is not on a quest to save a princess from some villain, but is trying to elucidate the mystery surrounding his father's death. This story was told through cutscenes which were simply amazing at the time. They were detailed, well directed, and full of intrigue. Negative Worlders, you may just play through this game for the story.