History YMMV / NinjaGaiden

** In the [[OriginalVideoAnimation anime movie]] based on the original NES trilogy, Professor Bucky-Wise is a [[BitchInSheepsClothing seemingly-nice man]] who was really the [[TheManBehindTheMan hidden villain]] pulling the strings. Bucky-Wise recorded a power surge when [[TheProtagonist Ryu Hayabusa]] defeated a powerful demon, managing to capture some of its power. He forces his colleague Ned Friedman to help him perform bizarre experiments [[IHaveYourWife by kidnapping his daughter Katherine]], using the demon's power to create an army of genetically altered creatures. Bucky-Wise is [[TestedOnHumans experimenting on humans]], as Ryu and his friends discover that one of his labs has [[WouldHurtAChild babies in jars]] and a twisted, mutilated dead creature on the ground. Bucky-Wise has his monsters attack Ryu and, when they fail to kill him, he kidnaps Ryu's girlfriend, Irene Lew. Ryu goes to Ned Friedman's corporation, believing he kidnapped her. Ryu confronts Ned, but Bucky-Wise kills him, [[YouHaveOutlivedYourUsefulness stating he is no longer useful to him]]. Bucky-Wise then tells Ryu he plans to release the same demon Ryu defeated on the world,[[TheEndOfTheWorldAsWeKnowIt not caring that this demon has the power to destroy humanity]]. Ryu kills Bucky-Wise and frees Katherine, but not before Bucky-Wise transferred some of the demon's power to her, [[DemonicPossession making her a vessel for the demon]]

** First game & ''The Dark Sword of Chaos'': [[BigBad Jaquio]], real name [[EvilSorcerer Guardia de Mieux]], wants to TakeOverTheWorld. Jaquio learns of a legend about a Demon that came to Earth 700 years ago and went on a killing spree until it was defeated by a Shinobi. The Demon's body was [[SealedEvilInACan imprisoned in a temple]] and its spirit was trapped in 2 different statues. Jaquio plans to free the Demon, believing it will grant him great power. Jaquio takes over the temple ruins, kills archeologist Walter Smith and kidnaps Ryu's father Joe in order to obtain the statues. When [[PlayerCharacter Ryu Hayabusa]] confronts Jaquio, the latter threatens to kill CIA agent [[LoveInterest Irene Lew]] if Ryu doesn't give him the statue, planning to sacrifice her anyway after Ryu gives him the statue. When Ryu confronts Jaquio again, Jaquio reveals he has made Joe his mind-controlled puppet and gleefully has him attack Ryu. Ryu seemingly kills Jaquio, but Jaquio is revived by evil magic. Jaquio obtains the Sword of Chaos and the Altar of Darkness that will allow him to open a portal and [[HellOnEarth allow a horde of demons to enter Earth, dooming mankind in the process]]. Jaquio attacks Ryu through his pawn Ashtar, and plans to [[HumanSacrifice sacrifice]] Irene and Ryu to summon the demons to Earth.
** ''The Ancient Ship of Doom'': [[TheManBehindTheMan H.P. Clancy]] is an assistant to CIA agent A. Foster and the hidden true villain of the game. After hero Ryu Hayabusa slew the evil wizard Jaquio and a demon he summoned, the demon's destruction created a portal to another dimension that is releasing energy. Foster takes over what is left of Jaquio's fortress in the Amazon and renames it Castle Rock Fortress. Clancy and Foster begin to use the other-dimensional energy to [[EvilutionaryBiologist perform experiments]], setting up a lab to create nightmarish creatures called Bio-Noids. When Ryu's girlfriend, CIA agent Irene Lew, was investigating the lab, Clancy has a Bio-Noid that looks like Ryu seemingly kill Irene and then [[FrameUp frames]] Ryu for her murder. After Ryu investigates the lab, Clancy approaches him and appears friendly, [[TreacherousQuestGiver directing him]] to go to the Castle Rock Fortress, saying he cannot condone Foster's experiments. When Ryu confronts Foster, Clancy reveals his true intentions, he will go into the dimensional portal and claim the energy for himself. When Ryu later confronts Clancy in the portal, Clancy reveals his master plan to use an ancient alien warship to [[KillAllHumans destroy humanity]] and replace them with Bio-Noid creatures.

** ''Ninja Gaiden Black'': [[EvilUncle Murai]] stands out as a truly horrible individual. Once part of the Hayabusa Clan, Murai defected from the group and plotted their demise. Being a neutral ally of the Hayabusas, Murai used his position and knowledge to sell them out to [[DemonKing Emperor Vigoor]] under the guise of the Dark Disciple while luring away his nephew, hero Ryu Hayabusa, during the scheduled invasion. With the Hayabusa Clan decimated and their ancient artifact, the Dragon Blade, in the hands a vengeful Ryu, Murai [[ManipulativeBastard sends him out]] to hunt after Vigoor to get revenge. This is actually so Ryu would increase the power of the the Dragon Blade through the blood of Emperor Vigoor's forces. He and his servant Gamov then kept watch and helped increase the number of demons so it would fuel the Dragon Blade, despite the collateral damage it would leave. After Emperor Vigoor is killed by Ryu as Murai expected, Murai reveals himself as [[TheManBehindTheMan the true villain]] and steals the sword away from Ryu, and [[YouHaveOutlivedYourUsefulness backstabs his loyal servant Gamov]]. He then tries to kill off Ryu and intends to take control of the world with the sword. Manipulative and traitorous, Murai would [[AmbitionIsEvil betray and slaughter anyone for power]].
** ''Ninja Gaiden 3'': [[MadScientist Clifford "Cliff" Higgins]] at first seems like a helpful scientist working for the Japanese Defense Force. However, Cliff is really working for the [[EvilutionaryBiologist Lords of Alchemy]], a group that wants to [[KillAllHumans destroy the human race]] and replace it with new "perfect" god-like beings; he is also the grandson of the head of the LOA. When Cliff's brother Theodore opposed Cliff's plans, Cliff had him killed in an [[MakeItLookLikeAnAccident accident]]. Cliff later decides to bring his brother back to life, [[BrainwashedAndCrazy brainwashes]] him and turns him into a terrorist. While under Cliff's control, Theodore launches a terrorist attack on London and murders the British Prime Minister. Cliff's plans come to a head when he uses his technology and hero Ryu Hayabusa's Dragon Sword, to turn Canna, [[EvilUncle his own niece]], into an EldritchAbomination called the Goddess. The Goddess then proceeds to go on a rampage across Tokyo, and will eventually destroy the entire human race. Later, after a fight with Ryu and a fatal injury at the hands of his brother, Cliff admits he did all this because he was [[DrivenByEnvy jealous of his brother]] and wanted to step out from under his shadow, any way he could.

** ''Ninja Gaiden 3'': [[BigBad Clifford "Cliff" Higgins]] at first seems like a helpful scientist working for the Japanese Defense Force. However, Cliff is really working for the [[EvilutionaryBiologist Lords of Alchemy]], a group that wants to [[KillAllHumans destroy the human race]] and replace it with new "perfect" god-like beings; he is also the grandson of the head of the LOA. When Cliff's brother Theodore opposed Cliff's plans, Cliff had him killed in an [[MakeItLookLikeAnAccident accident]]. Cliff later decides to bring his brother back to life, [[BrainwashedAndCrazy brainwashes]] him and turns him into a terrorist. While under Cliff's control, Theodore launches a terrorist attack on London and murders the British Prime Minister. Cliff's plans come to a head when he uses his technology and hero Ryu Hayabusa's Dragon Sword, to turn Canna, [[EvilUncle his own niece]], into an EldritchAbomination called the Goddess. The Goddess then proceeds to go on a rampage across Tokyo, and will eventually destroy the entire human race. Later, after a fight with Ryu and a fatal injury at the hands of his brother, Cliff admits he did all this because he was [[DrivenByEnvy jealous of his brother]] and wanted to step out from under his shadow, any way he could.

** ''The Ancient Ship of Doom'': [[TheManBehindTheMan H.P. Clancy]] is an assistant to CIA agent A. Foster and the hidden true villain of the game. After hero Ryu Hayabusa slew the evil wizard Jaquio and a demon he summoned, the demon's destruction created a portal to another dimension that is releasing energy. Foster takes over what is left of Jaquio's fortress in the Amazon and renames it Castle Rock Fortress. Clancy and Foster begin to use the other-dimensional energy to [[EvilutionaryBiologist perform experiments, setting up a lab to create nightmarish creatures called Bio-Noids]]. When Ryu's girlfriend, CIA agent Irene Lew, was investigating the lab, Clancy has a Bio-Noid that looks like Ryu seemingly kill Irene and then [[FrameUp frames Ryu for her murder]]. After Ryu investigates the lab, Clancy approaches him and appears friendly, [[TreacherousQuestGiver directing him to go to the Castle Rock Fortress]], saying he cannot condone Foster's experiments. When Ryu confronts Foster, Clancy reveals his true intentions: he will go into the dimensional portal and claim the energy for himself. When Ryu later confronts Clancy in the portal, Clancy reveals his master plan to use an ancient alien warship to [[KillAandReplace destroy humanity]] and replace them with Bio-Noid creatures]].

* PortingDisaster: The PC release for ''The Master Collection'' was criticzed by players and critics alike. The game launching windowed everytime, requiring one manually maximize it to enter fullscreen. The usual PC options are non-existant, requiring players to modify the launch propteries on Steam. And even then, it only supports 3 resolutions (720p, 1080p and 4K). This, combined, with a total lack of mouse & keyboard support, resulted in a port seen as barebones at best.

* PortinDisaster: The PC release for ''The Master Collection'' was criticzed by players and critics alike. The game launching windowed everytime, requiring one manually maximize it to enter fullscreen. The usual PC options are non-existant, requiring players to modify the launch propteries on Steam. And even then, it only supports 3 resolutions (720p, 1080p and 4K). This, combined, with a total lack of mouse & keyboard support, resulted in a port seen as barebones at best.

* ObviousJudas: Turns out [[EvilUncle Murai]], who ''in his very first scene'' talked about how much of a shame it was that the [[ArtifactOfDoom Dark Dragon Blade]] wasn’t being used was the bad guy all along! [[SarcasmMode Who could have seen that coming]]?

* SequelDifficultySpike: Or rather "re-release difficulty spike" − the original Xbox ''Ninja Gaiden'' was hard but nothing pain-inducing. ''Black'' (and by extension ''Sigma'') cranked it up a couple notches by introducing new vicious enemies, giving pre-existing ones better AI (and a grappling maneveur for Black Spider Ninjas), throwing out the window what little MookChivalry they could have, significantly {{nerf}}ing overly efficient moves like the Counter or Flying Swallow and adding the utterly sadistic Master Ninja Mode.

** First game & ''The Dark Sword of Chaos'': [[BigBad Jaquio]], real name [[EvilSorcerer Guardia de Mieux]], wants to TakeOverTheWorld. Jaquio learns of a legend about a Demon that came to Earth 700 years and went on a killing spree until it was defeated by a Shinobi. The Demon's body was [[SealedEvilInACan imprisoned]] in a temple and its spirit was trapped in 2 different statues. Jaquio plans to free the Demon, believing it will grant him great power. Jaquio takes over the temple ruins and kills archeologist Walter Smith and kidnaps Ryu's father Ken in order to obtain the statues. When [[PlayerCharacter Ryu Hayabusa]] confronts Jaquio, the latter threatens to kill CIA agent [[LoveInterest Irene Lew]] if Ryu doesn't give him the statue, planning to sacrifice her anyway after Ryu gives him the statue. When Ryu confronts Jaquio again, Jaquio reveals he has made Ken his mind-controlled puppet and gleefully has him attack Ryu. Ryu seemingly kills Jaquio, but Jaquio is revived by evil magic. Jaquio obtains the Sword of Chaos and the Altar of Darkness that will allow him to open a portal and [[HellOnEarth allow a horde of demons to enter Earth, dooming mankind in the process]]. Jaquio attacks Ryu through his pawn Ashtar, and plans to [[HumanSacrifice sacrifice]] Irene and Ryu to summon the demons to Earth.
** ''The Ancient Ship of Doom'': [[TheManBehindTheMan H.P. Clancy]] is an assistant to CIA agent A. Foster and the hidden true villain of the game. After hero Ryu Hayabusa slew the evil wizard Jaquio and a demon he summoned, the demon's destruction created a portal to another dimension that is releasing energy. Foster takes over what is left of Jaquio's fortress in the Amazon and renames it Castle Rock Fortress. Clancy and Foster begin to use the other-dimensional energy to [[EvilutionaryBiologist perform experiments]], setting up a lab to create nightmarish creatures called Bio-Noids. When Ryu's girlfriend, CIA agent Irene Lew, was investigating the lab, Clancy has a Bio-Noid that looks like Ryu seemingly kill Irene and then [[FrameUp frames]] Ryu for her murder. After Ryu investigates the lab, Clancy approaches him and appears friendly, [[TreacherousQuestGiver directing him]] to go to the Castle Rock Fortress, saying he cannot condone Foster's experiments. When Ryu confronts Foster, Clancy reveals his true intentions, he will go into the dimensional portal and claim the energy for himself. When Ryu later confronts Clancy in the portal, Clancy reveals his master plan to use an ancient alien warship to [[KillAllHumans destroy humanity]] and replace them with Bio-Noid creatures.

* MemeticMutation: "Just a girl. Get out of here!"[[note]]What Ryu says in the NES ''Ninja Gaiden'' during his first encounter with Irene; without context, it almost sounds as if Ryu was being a misogynist[[/note]]

* ScrappyMechanic: A lot of problems, death pits and enemy hazards in the original trilogy could've been negated if Ryu could mantle up the top of whatever walls he climbs. He can't, so you need to jump between adjacent surfaces or hop off to a nearby platform and ''then'' jump higher than the prior wall. A few cases in the trilogy even have tight jumps where even if you catch the wall above a pit, you can't climb ''up'' it to safety, so your life is forfeit anyway. At least the first game only had the basic wall cling, so it made more sense for this limitation, but the sequels are fully willing to exploit this in stages with wind currents, where the only way to progress is to jump into the current to reach the tops of platforms!

*** More specifically, 7-1 has wind currents impeding player progress and can cause frequent plummets off the stage to death if care isn't taken. While there is a "Fire Wheel" ninpo spell that can be acquired, it's the only one in all three of the sub-stages, and incredibly easy to lose either through dying or picking something else up by accident. 7-2, among other things, has traps looking like part of the background until players realize too late they took damage from it. Sure, there are two {{One Up}}s for this section, but the first one is difficult to get without dying in the process. Finally, 7-3 goes completely overboard with the SpikesOfDoom, placing them almost everywhere in screens that wouldn't be out of place in ''VideoGame/IWannaBeTheGuy''. Oh, and if players are looking for health potions, don't bother: there's not a single one in the entire stage. Perhaps the only saving grace is unlike the first NES game, losing to the FinalBoss won't send players back to 7-1, but the sub-stages being so obtuse and the fact players have finite continues in this game make it much more problematic, though not one they'll have to repeat if they mess something up at the FinalBoss.
* TheyCopiedItSoItSucks: {{Averted}} with the NES trilogy - people have noted the games copy a lot of things from ''Franchise/{{Castlevania}}'', most obviously the life bars, but most players agree the ''Ninja Gaiden'' games back then were still good in their own right despite the obvious influences. What likely helps is its {{Power Up}}s are fundamentally different from the ones seen in ''Castlevania''.

* ObviousJudas: Turns out [[EvilUncle Murai]], who ''in his very first scene'' talked about how much of a shame it was that the [[ArtifactOfDoom Dark Dragon Blade]] wasn’t being used and whose men can be found dead all over Tairon with [[ApocalypticLog journals that pretty much say he sent them there]], was the bad guy all along! [[SarcasmMode Who could have seen that coming]]?

** Actual bats: these critters do annoying damage and come in large packs, with ActionBomb variants showing up from ''Ninja Gaiden Black'' and onwards.

** While Team Ninja originally stated that the version of ''Sigma 2'' within the ''Master Collection'' would be based off the PS3 version, and thus lack the gore, fan outcry lead to a day one patch being released which added the gore back into ''Sigma 2''.

* AuthorsSavingThrow: Fan reception of ''Razor's Edge'' is much more positive than the original version of ''III'', thanks to its staggering amount of game-play changes, difficulty re-balancing and removing the worst aspects from the narrative of the original game.

* SuspiciouslySimilarSong: Two of them in the arcade version - the second stage almost sounds like "Bad" by Music/MichaelJackson and the second boss theme is very similar to "Iron Man" from Music/BlackSabbath. These connections are made even more apparent by their official titles from the OST ("PAT" and "I Am Man", respectively), as well as the fact that, starting with the Virtual Console version, all re-releases have outright removed "I Am Man".

* SeinfeldIsUnfunny: Not the gameplay, but the storyline. Someone watching the plots of the NES trilogy today will find them {{Narm}}y and overdone with their "three {{Plot Twist}}s per second" narrative, but the trilogy back then was considered a big leap forward for video game story-telling by having cut-scenes and fully-sentenced dialogue, coming all together for a coherent plot, compared to other games released during that generation.

* SeinfeldIsUnfunny: Someone watching the plots of the NES trilogy today will find them {{Narm}}y and overdone with their "three {{Plot Twist}}s per second" narrative, but the trilogy back then was considered a big leap forward for video game story-telling by having cut-scenes and fully-sentenced dialogue, coming all together for a coherent plot, compared to other games released during that generation.

* EightPointEight: IGN's '''3.0''' of ''Ninja Gaiden III'' gained quite a backlash, particularly their accusations of the game being a "technical disaster", which other critics didn't see as a major fault; rather, the less-than-stellar action and combat from its predecessors were the major problems. The UpdatedRerelease ''Razor's Edge'', however, got a much more decent 7.6.
* AccidentalInnuendo: During the cut-scene of Irene Lew [[spoiler:getting struck down by Ashtar]] in ''The Dark Sword of Chaos'', she slumps onto Ryu, but the way the animation does it makes it look like she's descending onto his crotch. Even the WebVideo/TheAngryVideoGameNerd in his review of ''Ninja Gaiden'' {{Discussed}} how unusual it looked.
* AdaptationDisplacement: {{Subverted}} - most fans who are aware of the two-player BeatEmUp version of the arcade installment believed it came out before the first UsefulNotes/NintendoEntertainmentSystem game. In reality, the arcade version was developed simultaneously with the latter; the two development teams making their own game based its core design on the same concept.

* AngstWhatAngst: In ''Ninja Gaiden III'', [[spoiler:upon being freed from the mask's control of his mind, Theodore Higgins doesn't seem to be fazed at all by all of the horrible things he was forced to do as the "Regent of the Mask", or the fact his brother and grandfather were the ones who forced him to do it, OR the fact his daughter is serving as the core for a giant monster ravaging Tokyo. {{Subverted}} in his last duel against Ryu Hayabusa as Theodore implies he was aware of everything that was going on while he was the Regent. He sacrifices himself not only to allow Ryu to free his daughter, but to receive his "[[MercyKill atonement]]" for his crimes as well]].
* AntiClimaxBoss:
** Although he's built up as TheDragon of the Holy Vigoor Emperor and the Greater Fiend who destroyed the Hayabusa Village by himself, Doku in the modern ''Ninja Gaiden'' is incredibly easy due to fixed attacks patterns; unlike Alma, his maneuvers are predictable and telegraphed. Even on "Master Ninja" difficulty of ''[[EnhancedRemake Ninja Gaiden Black]]'' is the fight against Doku [[https://www.youtube.com/watch?v=TobceDp3fho pathetically easy]].
** {{Zigzagged}} with the FinalBoss of the Xbox ''Ninja Gaiden'': [[spoiler:the Dark Disciple]], who claimed to have the power of the "Devil Incarnate", can be taken down through repeated use of the "Flying Swallow" technique when using the True Dragon Sword, which was a GameBreaker in the original release. However, ''Ninja Gaiden Black'' re-balanced the boss via {{Nerf}}ing the Flying Swallow.
** Considering roughly 70% of the game is spent chasing her down, Elizabét in ''Ninja Gaiden II'' isn't much of a challenge either, except her ThatOneAttack (see below): like Doku, her moves can be easily telegraphed and she often leaves her defenses open for exploits more than the other Greater Fiend bosses in the game. ''Sigma II'' rectified it by re-balancing her with the Greater Fiends and like the FinalBoss of the modern ''Ninja Gaiden'', spamming the same attacks from weapons won't do any good, including the Flying Swallow.
** The FinalBoss in ''Ninja Gaiden III'': not that the fight isn't visually impressive, but 30% of it is fighting {{Mook}}s [[FlunkyBoss the boss sends at players]], 30% are [[PressXToNotDie quick-time events]] with the remaining 40% the ''actual'' fight. Furthermore, the latter is fundamentally the same boss fight as the Statue of Liberty boss in ''Sigma II'', which veteran ''Ninja Gaiden'' players have no problem against, making this FinalBoss arguably the easiest one in the modern trilogy. Averted in ''Razor's Edge'' when it becomes part of ThatOneBoss for the game.
* AssPull: Obaba's comeback in ''Sigma II'' and ''III'' - the games don't bother explaining how she is revived when she's supposed to be KilledOffForReal in ''Dragon Sword''.
* AuthorsSavingThrow: Fan reception of ''Razor's Edge'' is much more positive than the original version of ''III'', thanks to its staggering amount of game-play changes, difficulty re-balancing and removing the worst aspects from the narrative of the original game.

* BigLippedAlligatorMoment: At the end of Day 5 in ''III'', a [[AttackOfTheFiftyFootWhatever colossal Obaba]] interrupts Ryu and Momiji who are on the way to see Joe Hayabusa via a boss fight. Not only is she and the Black Spider Ninja Clan not connected to the rest of the plot, they're never mentioned after the end of Day 5. ''Razor's Edge'' rectifies this by briefly noting the Black Spider are in cahoots with the "Lords of Alchemy" (LOA), yet the reason remains vague.

* BrokenBase:
** ''Sigma II'' - some consider it inferior to ''Ninja Gaiden II'' because of the lack of gore, easier difficulty and the removal of puzzles, but others consider it superior thanks to more balanced stage designs, less cheap AI, frame-rate fixes and the removal/revision of the most tedious passages of the original, as well as additional content of playable characters and game modes. The drastically reduced number of enemies and the introduction of a semi-automatic aim for the bow can be seen as a good ''or'' bad thing depending on who is asked.
** The story. Even if ''Ninja Gaiden'' revolutionized storytelling in video games since the NES era with its usage of cutscenes, it's mostly known for its hard and very punishing gameplay. For one camp, both are very important and they look forward if the story and world building could get good. But then there is a camp that believes that story is extremely unimportant and the series should focus on just making gameplay as tight and punishing as possible, and they could care less about the story getting to usually forgettable or SoBadItsGood as long as they can look awesome in slicing fiends off and getting very fierce when the other camp suggesting improvements on the stories. ''III''/''Razor's Edge'' showcased this quite prominently: By lessening the difficulty while creating a story that doesn't look like an ExcusePlot, it attracted the wrath of the second camp heavily, whereas while the first camp could agree on ''III'' being bad, they're more likely to forgive the improvement done by ''Razor's Edge''.

** [[UsefulNotes/NintendoEntertainmentSystem NES]] trilogy:
*** First game & ''The Dark Sword of Chaos'': [[BigBad Jaquio]], real name [[EvilSorcerer Guardia de Mieux]], wants to TakeOverTheWorld. Jaquio learns of a legend about a Demon that came to Earth 700 years and went on a killing spree until it was defeated by a Shinobi. The Demon's body was [[SealedEvilInACan imprisoned]] in a temple and its spirit was trapped in 2 different statues. Jaquio plans to free the Demon, believing it will grant him great power. Jaquio takes over the temple ruins and kills archeologist Walter Smith and kidnaps Ryu's father Ken in order to obtain the statues. When [[PlayerCharacter Ryu Hayabusa]] confronts Jaquio, the latter threatens to kill CIA agent [[LoveInterest Irene Lew]] if Ryu doesn't give him the statue, planning to sacrifice her anyway after Ryu gives him the statue. When Ryu confronts Jaquio again, Jaquio reveals he has made Ken his mind-controlled puppet and gleefully has him attack Ryu. Ryu seemingly kills Jaquio, but Jaquio is revived by evil magic. Jaquio obtains the Sword of Chaos and the Altar of Darkness that will allow him to open a portal and [[HellOnEarth allow a horde of demons to enter Earth, dooming mankind in the process]]. Jaquio attacks Ryu through his pawn Ashtar, and plans to [[HumanSacrifice sacrifice]] Irene and Ryu to summon the demons to Earth.
*** ''The Ancient Ship of Doom'': [[TheManBehindTheMan H.P. Clancy]] is an assistant to CIA agent A. Foster and the hidden true villain of the game. After hero Ryu Hayabusa slew the evil wizard Jaquio and a demon he summoned, the demon's destruction created a portal to another dimension that is releasing energy. Foster takes over what is left of Jaquio's fortress in the Amazon and renames it Castle Rock Fortress. Clancy and Foster begin to use the other-dimensional energy to [[EvilutionaryBiologist perform experiments]], setting up a lab to create nightmarish creatures called Bio-Noids. When Ryu's girlfriend, CIA agent Irene Lew, was investigating the lab, Clancy has a Bio-Noid that looks like Ryu seemingly kill Irene and then [[FrameUp frames]] Ryu for her murder. After Ryu investigates the lab, Clancy approaches him and appears friendly, [[TreacherousQuestGiver directing him]] to go to the Castle Rock Fortress, saying he cannot condone Foster's experiments. When Ryu confronts Foster, Clancy reveals his true intentions, he will go into the dimensional portal and claim the energy for himself. When Ryu later confronts Clancy in the portal, Clancy reveals his master plan to use an ancient alien warship to [[KillAllHumans destroy humanity]] and replace them with Bio-Noid creatures.
** Team Ninja series:
*** ''Ninja Gaiden Black'': [[EvilUncle Murai]] stands out as a truly horrible individual. Once part of the Hayabusa Clan, Murai defected from the group and plotted their demise. Being a neutral ally of the Hayabusas, Murai used his position and knowledge to sell them out to [[DemonKing Emperor Vigoor]] under the guise of the Dark Disciple while luring away his nephew, hero Ryu Hayabusa, during the scheduled invasion. With the Hayabusa Clan decimated and their ancient artifact, the Dragon Blade, in the hands a vengeful Ryu, Murai [[ManipulativeBastard sends him out]] to hunt after Vigoor to get revenge. This is actually so Ryu would increase the power of the the Dragon Blade through the blood of Emperor Vigoor's forces. He and his servant Gamov then kept watch and helped increase the number of demons so it would fuel the Dragon Blade, despite the collateral damage it would leave. After Emperor Vigoor is killed by Ryu as Murai expected, Murai reveals himself as [[TheManBehindTheMan the true villain]] and steals the sword away from Ryu, and [[YouHaveOutlivedYourUsefulness backstabs his loyal servant Gamov]]. He then tries to kill off Ryu and intends to take control of the world with the sword. Manipulative and traitorous, Murai would [[AmbitionIsEvil betray and slaughter anyone for power]].
*** ''Ninja Gaiden 3'': [[BigBad Clifford "Cliff" Higgins]] at first seems like a helpful scientist working for the Japanese Defense Force. However, Cliff is really working for the [[EvilutionaryBiologist Lords of Alchemy]], a group that wants to [[KillAllHumans destroy the human race]] and replace it with new "perfect" god-like beings; he is also the grandson of the head of the LOA. When Cliff's brother Theodore opposed Cliff's plans, Cliff had him killed in an [[MakeItLookLikeAnAccident accident]]. Cliff later decides to bring his brother back to life, [[BrainwashedAndCrazy brainwashes]] him and turns him into a terrorist. While under Cliff's control, Theodore launches a terrorist attack on London and murders the British Prime Minister. Cliff's plans come to a head when he uses his technology and hero Ryu Hayabusa's Dragon Sword, to turn Canna, [[EvilUncle his own niece]], into an EldritchAbomination called the Goddess. The Goddess then proceeds to go on a rampage across Tokyo, and will eventually destroy the entire human race. Later, after a fight with Ryu and a fatal injury at the hands of his brother, Cliff admits he did all this because he was [[DrivenByEnvy jealous of his brother]] and wanted to step out from under his shadow, any way he could.
*** ''VideoGame/YaibaNinjaGaidenZ'' {{spinoff}}: [[BigBad Alarico del Gonzo]] is the holographic [[CorruptCorporateExecutive head]] of Forge Industries, and the one responsible for the [[ZombieApocalypse zombie outbreak]]. Discovering an underground space lobster, he decided to harvest the chemical Substance 72 from it in order to cure his disease and become a God-like figure, unleashing the chemical onto Soviet soil once he hears of Ryu Hayabusa coming to stop him. Doing so causes everyone in Russia to become a zombie, with del Gonzo using them to distract Ryu. Resurrecting [[PlayerCharacter Yaiba Kamikaze]] as a cyborg, he has him hunt down Ryu so that he can activate Yaiba's [[ExplosiveLeash killswitch]] to detonate the two ninjas, killing some of his men in a fit of rage once that fails.
** Other Media:
*** ''Literature/WorldsOfPower'': [[BigBad Jacquio]], real name [[EvilSorcerer Guardia de Mieux]], is a demonic being who seeks to use the light and dark statues to awaken a powerful demon, harness its energy, and [[TakeOverTheWorld gain world domination]] with his demon army. Kidnapping Ken Hayabusa and making him his [[BrainwashedAndCrazy mind-controlled fighter]] after he and Dr. Wimpleton steal the statues, Jacquio sends thieves out to regain the statues, [[LackOfEmpathy uncaring of the casualties]]. With the teenage Ryu Hayabusa, Ken's son, inside his personal temple, Jacquio promises to kill CIA agent Irene Lew should he not get his dark statue back, forcing Ryu to fight his monsters after he complies. Seething with glee over forcing Ryu to fight his mutated, mind-controlled father, once he finds them reconciling, Jacquio attempts to kill them both and continue his world domination plan.
*** In the [[OriginalVideoAnimation anime movie]] based on the original NES trilogy, Professor Bucky-Wise is a [[BitchInSheepsClothing seemingly-nice man]] who was really the [[TheManBehindTheMan hidden villain]] pulling the strings. Bucky-Wise recorded a power surge when [[TheProtagonist Ryu Hayabusa]] defeated a powerful demon, managing to capture some of its power. He forces his colleague Ned Friedman to help him perform bizarre experiments [[IHaveYourWife by kidnapping his daughter Katherine]], using the demon's power to create an army of genetically altered creatures. Bucky-Wise is [[TestedOnHumans experimenting on humans]], as Ryu and his friends discover that one of his labs has [[WouldHurtAChild babies in jars]] and a twisted, mutilated dead creature on the ground. Bucky-Wise has his monsters attack Ryu and, when they fail to kill him, he kidnaps Ryu's girlfriend, Irene Lew. Ryu goes to Ned Friedman's corporation, believing he kidnapped her. Ryu confronts Ned, but Bucky-Wise kills him, [[YouHaveOutlivedYourUsefulness stating he is no longer useful to him]]. Bucky-Wise then tells Ryu he plans to release the same demon Ryu defeated on the world,[[TheEndOfTheWorldAsWeKnowIt not caring that this demon has the power to destroy humanity]]. Ryu kills Bucky-Wise and frees Katherine, but not before Bucky-Wise transferred some of the demon's power to her, [[DemonicPossession making her a vessel for the demon]]
* ContestedSequel: Yosuke Hayashi's drastically different vision for ''III'' left many fans skeptical. While some players believe it's still a fun ActionGame in its own right, if not, on par with the first two games, [[FanonDiscontinuity others prefer to pretend it never existed]] (interestingly, Hayashi was already involved in [[VideoGame/MetroidOtherM another]] ContestedSequel). ''Razor's Edge'' is unanimously considered an AuthorsSavingThrow, yet it also remains this in its own right, since some feel that while it rectified the shortcomings of ''III'', others feel ''Razor's Edge'' is still a bad game regardless of the improvements.
* CrossesTheLineTwice: ''Ninja Gaiden II'' is so ridiculously gory it practically skips the offensive and goes straight to hilarious. May or may not double as NarmCharm.
* DemonicSpiders
** Birds or any sort of avian/winged enemy in the NES trilogy: a large reason why they're so terrible, at least in the first game, is due to a glitch with how the game handles enemy spawns - anything that's in the exact position of the level will respawn as soon as it's taken out, causing them to infinitely respawn until players deliberately trek across the stage. The problem is, particularly in the first game, moving forward is not always a reasonable option.
** The "ghost piranhas" infesting the labyrinth in Zarkhan for the modern ''Ninja Gaiden'' due to pack-like tendencies, respawning capabilities and sheer, unimaginable attack speed and tenacity. Hilariously, they were originally decorative in the environment until director Tomonobu Itagaki found out about them and told the development team to make them enemies. By contrast, their difficulty is slightly toned down in the {{Sequel}}, with the exception of that one chapter where players must deal with them ''alongside'' the Water Dragon boss. However, this becomes noticeably easier in ''Sigma II''.
** In the first game of the modern trilogy, especially at the highest difficulties, a good portion of the non-human {{Mook}}s turn into this, such as the black "[[EyeBeams laser eye-firing]]" fiends or the feline-based fiends, thanks to their agility and lightning-fast attacks, especially when fought in groups.
** ''Ninja Gaiden II'' has a literal kind with Black Spider Ninja "Rasetsu": while he certainly doesn't count in his first appearance as a boss for the first level of the game, his derivatives turn into [[DegradedBoss common enemies]] later on, which do apply.
** Liked the GoddamnedBats in the first modern release? In ''Ninja Gaiden II'', meet giant bats! Thrice as big, deal thrice as much damage, are thrice as tough and are still unblockable. More often than not, players will take damage while trying to kill them.
** The infamous Incendiary Kunai Black Spider Ninjas from ''Ninja Gaiden II'' are usually this when fighting them in large groups; [[BulletHell take a guess why by looking at their name]]. Strangely, ''Sigma II'' kept them as this despite fewer on-screen enemies at a time, but for a different reason: though they use their explosives less often, they turn more resilient to attacks (an "[[SpinningPiledriver Izuna Drop]]" won't be enough to kill them at higher difficulties) and are much more competent at close combat instead. This turns especially jarring at higher difficulties where their claw attacks take off chunks of {{Hit Point}}s compared to the average Black Spider Ninja {{Mook}}.
** Alchemists in ''Ninja Gaiden III'' has a GroundPound-like maneuver that, while blockable, breaks guard and is hard to dodge most of the time. Furthermore, they're fast, agile, hurl homing "alchemy projectiles", block and evade often and frequently erect an "alchemy armor" that requires breaking it first before actual damage can be dealt, which light attacks from Ryu's weapons won't usually do; they also have a GrappleMove that not only slowly drains {{Hit Point}}s, but the ki gauge as well. Finally, in ''Razor's Edge'', the timing to perform a "Steel-on-Bone" CounterAttack is so exceptionally narrow compared to other humanoid enemies in the game that players will often opt out for dismemberment instead, allowing an "Obliteration Technique" to finish them off; unfortunately, Alchemists are the most resilient enemies in the game to be dismembered.
** Chimera in the later parts of ''Ninja Gaiden III'' are essentially faster, more evasive Incendiary Kunai Black Spider Ninja, with the only saving grace is they don't have projectiles. Like Alchemists, they too block occasionally and might get a bead on escaping out of players' attack combos more often than not. The problem with these Chimera comes if they're dismembered: doing so, and they initiate an unblockable SuicideAttack, homing straight for Ryu, forcing players to prioritize on dismembered Chimera for an Obliteration Technique lest they risk a chunk of {{Hit Point}}s getting taken away. Fortunately, it's easy to note if a suicide-Chimera will begin its strike as they start sparking bright colors; additionally, if they don't reach Ryu in time, the suicide-Chimera will wind up exploding - their effects don't have what an ActionBomb {{Mook}} usually does in this series.

* EnsembleDarkhorse:
** Robert T. Sturgeon in ''The Dark Sword of Chaos'' is a MysteriousInformant[=/=][[MysteriousProtector Protector]] with an agenda of his own, wears CoolShades and able to take down demonic horrors with a single gunshot, [[spoiler:who turns out to be a top United States Army operative and an extremely loyal ally to Ryu that he makes a LastStand to guard his back in the very bowels of Hell]]. This is especially notable considering how ''[[SarcasmMode well]]'' Ryu gets along with covert government agencies in other installments.
** Following their respective debuts, Rachel and Momiji: both garnered enough popularity to warrant not just subsequent reappearances in ''Ninja Gaiden'' {{Sequel}}s, but an [[CanonImmigrant immigration]] as {{Playable Character}}s in the ''VideoGame/DeadOrAlive'' franchise and the UpdatedRerelease versions of ''VideoGame/WarriorsOrochi''.
* EvilIsSexy: Elizabét, outside of her OneWingedAngel form, with OfCorsetsSexy in play; that she also bathes nude in a BloodBath in her last appearance certainly helps.
* FandomEnragingMisconception: The series' English-language title is pronounced "Ninja GUY-den," not "GAY-den." Getting this wrong used to be one of the more sure-fire ways to piss off its fans.
* FanonDiscontinuity: The original ''Ninja Gaiden III'' is usually ignored, and ''Razor's Edge'' is seen by most players as the "real" version of the third game; however, that's without considering those who didn't even like ''Razor's Edge'' regardless.
* FashionVictimVillain: The Regent of the Mask - having an outfit consisting of a red BadassLongcoat, a CoolMask, a [[InTheHood mysterious hood]] and a gold-plated GlovedFistOfDoom can only make him one. To compliment this trope, he's armed with a RoyalRapier.
* FirstInstallmentWins: Although ''The Dark Sword of Chaos'' and ''The Ancient Ship of Doom'' have many game-play refinements, most people will jump back to the original NES ''Ninja Gaiden'' before the other two when it's the most recognizable of the trilogy in terms of DemonicSpiders in conjunction with PlatformHell, as well as the more easier of the digestable plots.
** As well-received as ''Ninja Gaiden II'' was, the 2004 game is near-unanimously considered to be the best of the modern series, as well as the one most non-fans remember.
* GameBreaker
** The Windmill Technique from the NES ''Ninja Gaiden'', capable of killing every single {{Mook}} (and boss) in the game with one use, [[AwesomeButImpractical that is, provided players can plow through an entire level heading towards the boss with minimal jumping attacks or getting other power ups, as each jumping attack triggers the Windmill Technique and eats up ninpo power]]. However, it's still possible to execute a normal jump attack by holding down while attacking.
** The "[[MagikarpPower Unlaboured Flawlessness]]" in the modern ''Ninja Gaiden'': players who are skilled enough to stay alive at 15% health can cut enemies down with this weapon at shocking speeds. On the other hand, given the [[DesperationAttack strict health requirement]] and the game's difficulty, this isn't as severe as the others listed.
** The Izuna Drop in all modern appearances is fairly easy to execute and will instantly kill any human-sized {{Mook}} at lower difficulties: in the first game, enemies often block and players can only perform the technique with "katana-like" weapons, making its use restricted. However, the sequel ensures almost all weapons have access to an Izuna Drop of one form or another, and enemies don't guard at all from it. Rectified in ''Sigma II'' by {{Nerf}}ing it slightly via making some {{Mook}}s (almost all of them on Master Ninja difficulty) resilient enough to survive it.
** The Flying Swallow was overpowered in the original version of the modern ''Ninja Gaiden'', to the point where it would make short work of enemies and even some bosses; the FinalBoss could even be cheesed by simply spamming it. Addressed in ''Ninja Gaiden Black'' where as the Flying Swallow was {{Nerf}}ed extensively: enemies and bosses could now block it, and they would do so more often on harder difficulties; ''Black'' even goes so far as to include enemies that punish players for relying on the technique too much.
** "Ultimate Techniques" in the modern trilogy are a similar case: in the first game, without absorbing essence to speed it up, it takes several seconds to charge a full-powered Ultimate Technique and their effective range is limited. In ''Ninja Gaiden II'' and ''Sigma II'', it takes half the time to activate, with some weapons' Ultimate Techniques being ''glaringly'' over-effective on large groups of small {{Mook}}s.
** The "[[DownloadableContent Hurricane Packs]]" for the modern ''Ninja Gaiden'' added an "Intercept" maneuver where Ryu can parry any enemy attack and trigger a CounterAttack via Ultimate Technique if players can get the proper timing down. It's no wonder Intercept's effectiveness wound up being removed in ''Ninja Gaiden Black''.
** The "[[SinisterScythe Eclipse Scythe]]" in ''III'', despite its slow attack speed, can become this if used properly. With the Dragon Sword or the "[[WolverineClaws Falcon's Talons]]", players can directly repeat successful Steel-on-Bone attacks on nearby enemies. The scythe, however, has the longest reach of all available weapons in the game[[note]]The scythe and claws were DownloadableContent in ''III''[[/note]], meaning "nearby enemy" entails into "any enemy within a large, encompassing radius". As long as players don't screw up the initial Steel-on-Bone strike, taking down entire waves of {{Mook}}s can be done almost effortlessly. As of ''Razor's Edge'', the scythe has taken this completely, being the only weapon used by players more than the Dragon Sword against groups of {{Mook}}s. However, it suffers from a few drawbacks, notably a limit to the number of successive Steel-on-Bone attacks thanks to ''Razor's Edge" rectifying game-play and the inertia after every regular strike of the weapon.
** Speaking of the revamped Steel-on-Bone system in ''Razor's Edge'', provided players take the time to properly use it via {{Counter Attack}}s, {{Mook}}s bum-rushing players will mean nothing if players can spot the tell from enemies that allows a Steel-On-Bone to trigger. Furthermore, having low {{Hit Point}}s won't mean a thing either since successive Steel-On-Bone strikes also grant RegeneratingHealth.

** Actual bats for the modern games: these critters do annoying damage and come in large packs, with ActionBomb variants showing up from ''Ninja Gaiden Black'' and onwards.
** Bats are also regular enemies in the NES trilogy, and they're in all respects similar to ''VideoGame/CastlevaniaI'' bats.
** Birds in the NES trilogy: while bats at least fly in a predictable pattern and usually aren't difficult to avoid, birds actively home in on Ryu's position and are almost always by [[LedgeBats ledges]] and {{Bottomless Pit}}s. In the first game, they take three slots off the life bar, making them the highest damage-dealers in the game that aren't bosses.
** The "jellyfish" in the Amazon level for ''Ninja Gaiden II'': sure, they don't move and are easy to eliminate with ranged weapons, but they get in the way and never stop spawning. Of course, the alternative is simply to swim through them, but [[MadeOfExplodium that's at the player's own risk]].
** Appearing first in the same level are the large killer fish: similar to the jellyfish, players wil need to use the speargun, but unlike the former, these creatures are more durable and aggressive. In the Amazon level, there is a small section where players can hang back where they can't reach out Ryu so potshots can be taken against them instead; unfortunately, when they reappear in the final level of the game, players are likely out of luck since there's no avoiding them.
** Dogs, the blue bugs and the human-like homunculi (pre-transformation into its "gorilla" or "snake" forms) often act as this in ''Razor's Edge'': while they aren't necessarily hard to defeat, the former two are just as agile as humanoid {{Mook}}s, while the latter have more {{Hit Point}}s than they appear.
* GoddamnedBoss: Two examples from ''Ninja Gaiden II''
** The infamous giant worm boss at the end of the Amazon level: by no means is it difficult - it's simply horribly ill-designed, as 90% of the fight ensures players are unable to see it, even when they're hitting it, due to the boss tunneling itself and popping out from any direction without a sign for players to know where. ''Sigma II'' didn't even try to make it better when Team Ninja mercifully removed it from the level, along with the entire "green tunnel" section leading up to the boss and after defeating it. Those who haven't played ''Ninja Gaiden II'' and only ''Sigma II'' wouldn't even notice its absence.
** The two "armadillo" bosses in the first underworld level: the words "CameraScrew" will mean something until players have gone through this fight, which stands in contrast to the first armadillo boss at the end of the aircraft level. Like the above, ''Sigma II'' removed it, replacing it with a fight against Marbus instead.
* GoodBadBugs: In ''Razor's Edge'', Kasumi has a version of the "Cicada Surge" technique called "Sakura Madoi", allowing her to evade not only melee attacks like Ryu, but also bullets and missiles, meaning it's possible to use Sakura Madoi to teleport into areas normally inaccessible, and in extreme cases, ''out of the map''. This was fixed when the re-release was ported to the Sony UsefulNotes/PlayStation3 and Microsoft UsefulNotes/Xbox360.
* HamAndCheese: The plot and dialogue of ''Ninja Gaiden III'' are nothing to write home about but James Brinkley is very obviously having a blast as the Regent of the Mask. He's arguably the most memorable villain of the franchise just for how gloriously over the top he is.
* HilariousInHindsight
** The simple fact this series is called ''Ninja Gaiden'' ("gaiden" meaning "side-story") due to RuleOfCool becomes hilarious these days now that Creator/KoeiTecmo state it's a side-story to ''VideoGame/DeadOrAlive'', despite ''Ninja Gaiden'' [[OlderThanTheyThink having been around a lot longer than]] the latter.[[labelnote:However...]]The statement makes much more sense when you realize that only the modern post-2004 series was called "Ninja Gaiden" in Japan and PAL regions; the NES and arcade games had different titles there.[[/labelnote]]
** HilarityEnsues with ''VideoGame/YaibaNinjaGaidenZ'', which is a side-story for the modern ''Ninja Gaiden'' trilogy, bringing the trope GaidenGame full circle.
* ItsEasySoItSucks: ''Ninja Gaiden III'' is such a far cry from its punishing predecessors that it would take ''Razor's Edge'' to ratchet the difficulty back up to normal, yet it keeps the easier "Hero" mode as a play-style that can be selected at any time.
* LauncherOfAThousandShips: Ryu is frequently paired with Irene, Rachel, Momiji, Ayane or [[VideoGame/DeadOrAlive Kasumi]] in fanfic. [[BattleHarem Sometimes all of them at once]].
* MemeticMutation
** "Just a girl. Get out of here!"[[note]]What Ryu says in the NES ''Ninja Gaiden'' during his first encounter with Irene; without context, it almost sounds as if Ryu was being a misogynist[[/note]]
** [[LargeHam Why? BUSINESS OF COURSE!]][[note]]When asked by Ryu about the cloned dinosaurs in the Day 3 level of ''Ninja Gaiden III'', the Regent of the Mask over-exaggerates his answer with these words[[/note]]
** Lovelace Gaga[[note]]An obvious reference to the character Lovelace's uncanny resemblance to Music/LadyGaga in ''Ninja Gaiden III''[[/note]]
** "[[SuspiciouslySimilarSong I Am Man]]"[[note]]The boss music for the second stage in the arcade ''Ninja Gaiden'' game sounds too similar to Music/BlackSabbath's "Iron Man", and the name of the song, "I Am Man", doesn't even try to hide the fact that it is.[[/note]]
* {{Narm}}
** The ''Literature/WorldsOfPower'' book is filled with this, starting with the acknowledgement on the first page, "Dedicated to the ninja in everyone's dad".
** The original arcade game is rife with this at the "round clear" screens of each stage. Specific mention is its premise: [[ExcusePlot a seemingly random]] [[GratuitousNinja ninja]] [[ExcusePlot who happens to be Ryu goes to America]] ("NINJA IN U.S.A.") [[ExcusePlot to beat the crap out of an evil cult]] full of hockey-mask wearing thugs, sumo and normal wrestlers alike, and various others, all led by "Bladedamus", a descendant of UsefulNotes/{{Nostradamus}} clad in BDSM gear and with a mural of death and a similarly-clad man's ass in his throne room. One of the clear cards even depicts Ryu cheerfully messing up a window cleaner's work (and spooking them), and another has him shooting craps at a casino table, clad in a [[RealMenWearPink pink suit]] and surrounded by PlayboyBunny girls!
** The "don't kill me mate" scene at the beginning of the Day 1 level in ''Ninja Gaiden III'' is so overdone and theatrical it winds up being hilarious instead of an intended PlayerPunch. Team Ninja must have taken notes as the scene is removed in ''Razor's Edge''.
*** ''Ninja Gaiden III'' as a whole is so {{Main/Anvilicious}} about its “Feel their pain/killing is bad” message that it crosses the line straight into unintentional hilarity.
* NightmareFuel
** About the only thing anybody knows about the original arcade machine is the circular saw from the continue screen.
** Also from the arcade installment, the shadow of Ryu behind a window at the start of every stage, with RedEyesTakeWarning before he bursts through the screen and starts the level.

** How about the [[https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAQQjBw&url=https%3A%2F%2Fvgmdaily.files.wordpress.com%2F2010%2F05%2Fngaiden149.png&ei=lLAgVe5Myd2wBYm8gdgO&bvm=bv.89947451,d.b2w&psig=AFQjCNFoctlK78fXoaOHpM3czxC4Gcbo6w&ust=1428292096961254 Masked Devil]] from the first NES game?
** Professor Bucky-Wise's OneWingedAngel transformation in the OVA: [[BodyHorror his skin peels off and he grows a second backbone as his human features fall off]] ([[{{Squick}} his ears and eyes can be seen falling off and melting, respectively]]) as he becomes a green skinned HumanoidAbomination. The apperance itself is incredibly sadistic, stabbing Ryu in the arm and crushing Irene's arm when she tries to save Ryu, [[SlasherSmile all the while it's smiling]].
* ObviousJudas:
** Turns out [[EvilUncle Murai]], who ''in his very first scene'' talked about how much of a shame it was that the [[ArtifactOfDoom Dark Dragon Blade]] wasn’t being used and whose men can be found dead all over Tairon with [[ApocalypticLog journals that pretty much say he sent them there]], was the bad guy all along! [[SarcasmMode Who could have seen that coming]]?
** ''Ninja Gaiden'' as a whole is notorious for this: seemingly friendly characters that turn out to be villains in “twists” that have ludicrously heavy amounts of {{Main/Foreshadowing}}: the aforementioned Murai, Foster and Clancy from the original Ninja Gaiden NES trilogy, Cliff Higgins from ''III'', Professor Bucky-Wise from the OVA, and Alaricio del Gonzo from ''Yaiba''.
* OnlyTheCreatorDoesItRight: What certain fans think about the modern trilogy and one of the reasons there's so much bashing on the games where Hayashi was involved (''Sigma'', ''Sigma II'' and ''III'') - any title not directed by Itagaki can only be a pale imitation. It doesn't help that before leaving Team Ninja pre-merger, Itagaki specifically said he didn't like ''Sigma'', that ''Ninja Gaiden II'' was the definitive version of the game and he was the only one legitimate enough to continue the series.
* PlayerPunch:
** The various journals you can find on the bodies of dead ninja throughout the games often reveal that, though they may have been part of enemy clans, they were just as brave and determined to succeed as Ryu. Sometimes they even display thoughtfulness and internal conflict about what they're doing.
** ''Ninja Gaiden III'' goes to great length to make players feel the pain of the enemies they kill, be it the brutal Steel-on-Bone mechanic or the moaning of enemies if they aren't finished off as they crawl helplessly on the ground, bleeding to death.
-->'''Crawling and bleeding {{Mook|s}}''': "''I don't wanna die...I don't wanna die!''"
* PlayTheGameSkipTheStory: The story of every ''Ninja Gaiden'' game is pretty much an ExcusePlot to have Ryu Hayabusa running around and slicing people up in stylish ways. One may be forgiven for having trouble even remembering what sets Ryu on his bloody path in any of the games as you're dishing out flashy combos of death left and right.
* PolishedPort: {{Zigzagged}} for ''Razor's Edge'' - apart from the addition of several weapons, upgrades, collectible items and playable characters, nearly every aspect of the ''Ninja Gaiden III'' game-play has been improved, from {{Combo}} speed to weapon responsiveness, to enemy AI, to the use of the ki bar and the revamped Steel-on-Bone mechanic, making the game much more technical; the [=PlayStation=] 3/Xbox 360 ports also corrects the frame-rate drops from the Creator/{{Nintendo}} UsefulNotes/WiiU version. Thus, while ''Razor's Edge'' seems to play this straight, it's {{Subverted}} when it still contains unusual bugs and glitches, such as the "[[https://www.youtube.com/watch?v=430r4wx2ldg infinite karma]]" glitch.
* ScrappyMechanic
** A lot of problems, death pits and enemy hazards in the original NES trilogy could've been negated if Ryu could mantle up the top of whatever walls he climbs. He can't, so you need to jump between adjacent surfaces or hop off to a nearby platform and ''then'' jump higher than the prior wall. A few cases in the trilogy even have tight jumps where even if you catch the wall above a pit, you can't climb ''up'' it to safety, so your life is forfeit anyway. At least the first game only had the basic wall cling, so it made more sense for this limitation, but the sequels are fully willing to exploit this in stages with wind currents, where the only way to progress is to jump into the current to reach the tops of platforms!
** The save system in the modern ''Ninja Gaiden'' makes it so that if players die, they restart at the last save point, no exception. This means if they die fighting a boss, they must redo any section between the save point all the way to the boss again; additional redundancy occurs if death happens at the beginning of the next chapter without having saved the game, where they must fight the boss from the previous chapter again.
** The Steel-on-Bone mechanic in ''Ninja Gaiden III'' was largely unnecessary due to it randomly activating in the middle of striking enemies and can interrupt {{Combo}}s. Rectified in ''Razor's Edge'' where Steel-on-Bone is used as a form of CounterAttack to prevent enemy {{Grapple Move}}s.

* SequelDifficultyDrop: A good part of the bashing ''Ninja Gaiden III'' received is [[ItsEasySoItSucks due to this]]. The thing is, Hard Mode is still just as brutal as ever, so the jump between Normal and Hard is pretty steep.
* SequelDifficultySpike: Or rather "re-release difficulty spike" − the original Xbox ''Ninja Gaiden'' was hard but nothing pain-inducing. ''Black'' (and by extension ''Sigma'') cranked it up a couple notches by introducing new vicious enemies, giving pre-existing ones better AI (and a grappling maneveur for Black Spider Ninjas), throwing out the window what little MookChivalry they could have, significantly {{nerf}}ing overly efficient moves like the Counter or Flying Swallow and adding the utterly sadistic Master Ninja Mode.
* SoBadItsGood: Whatever fans think of the respective plots of the modern installments - ''Dragon Sword'' and ''III''[=/=]''Razor's Edge'' have a little more detailed ones, not that this saves the latter from being a ContestedSequel, though.
* SuspiciouslySimilarSong: Two of them in the arcade version - the second stage almost sounds like "Bad" by Music/MichaelJackson and the second boss theme is very similar to "Iron Man" from Music/BlackSabbath. These connections are made even more apparent by their official titles from the OST ("PAT" and "I Am Man", respectively), as well as the fact that, starting with the Virtual Console version, all re-releases have outright removed "I Am Man".
* ThatOneAchievement: It's literally impossible to obtain the platinum trophy for the Sony UsefulNotes/PlaystationVita version of ''Sigma II Plus'', as "Tag Mode" forces players to partner with the AI since CooperativeMultiplayer was removed. At least three missions ''demand'' two human players work in concert, which cannot happen if one of them is an AI-controlled character.
* ThatOneAttack: Two examples from ''Ninja Gaiden II''
** Zedonius' flame wall is unblockable and cannot be avoided at close range; even some moves with invulnerability frames cannot provide protection. The only thing players can do against it is casting ninpo spells, but if ninpo stocks are out, pray he doesn't use it. The only reasonable way to truly evade it otherwise is to stay the hell away from Zedonius as much as possible.
** Elizabét's "blood orbs" are similarly hard to dodge, unblockable, deals the largest damage from her arsenal of attacks, can place players into a {{Stunlock}} such that they'll be hit by the next orb AND [[CastFromHitPoints heals Elizabét the more the attack deals damage]].
* ThatOneBoss: Just about every single one of them, especially in the modern games.
** Bloody Malth in the first NES game throws lightning fast homing projectiles that are nearly impossible to dodge. Unless players have god-like timing, the fight is more than likely going to boil down to a war of attrition. Meanwhile, good luck getting to the fight ensuring Ryu has full health by the time players get to Bloody Malth.
*** Since the battle follows a cutscene, players start the BossFight with a full health bar. Because of that, the best strategy really is to just rush him and mash the attack button. It could be considered an act of mercy if there were any evidence the developers were capable of such a thing.
** Murai in the modern ''Ninja Gaiden'', not because he's the WarmUpBoss, but rather he's a WakeUpCallBoss.
** The first fight with Alma from the same game is often regarded as the toughest at that point due to aerial, agile strikes, unpredictable attack patterns, high-damage maneuvers (some of them unblockable) and high-resilience to almost all weapons in Ryu's arsenal at that point in the game. The later [[OneWingedAngel Awakened Alma]] BossFight before the climax is worse when these attributes are also carried over; the [[InfinityPlusOneSword True Dragon Sword]] or the Unlaboured Flawlessness won't be of much help.
** ''Ninja Gaiden II'' has pretty brutal bosses, but Zedonius takes the cake, especially the rematch against him in the underworld. While the other three Greater Fiend bosses should have the same difficulty, and are fought in similar arenas to the original duels, Zedonius takes players on a series of rather small rock out-croppings floating in a big lake of magma. As the "[[RedBaron Ruler of Flame]]", he's fireproof; Ryu's not, and since the previous boss fight with him forced Zedonius to use primarily-ranged attacks in a relatively-confined space of a clock tower, unwary players will quickly learn this is no longer the case when he starts teleporting miles away to open up with his flames, particularly ThatOneAttack.
** The Regent of the Mask in ''III'' and ''Razor's Edge'', another WakeUpCallBoss akin to Murai, except he's also an SNKBoss who blocks almost every attack players do, is less exploitable than other bosses in the game, and can NoSell attacks. Without careful thinking on when to strike, expect to be brutally punished for it if players don't have the patience to time their attacks correctly.
** Provided players wish to tackle "Ninja Trials" in ''III'' and "Test of Valor" in ''Razor's Edge'', Marbus, but for a different reason: due to the lack of a controllable boss camera angle (introduced in ''Sigma II'', but strangely absent in ''III''), players face him 50% of the time off-screen. Thankfully, ''Razor's Edge'' brought the feature back, but that doesn't mean Marbus still isn't as tough as he was in previous installments. Furthermore, he's riddled with glitches, which is noticeable when doing online Ninja Trials with a partner (human or AI).
** The FinalBoss of ''Razor's Edge'', in sharp contrast to its vanilla version in ''III'': the first phase of it is notorious for being extremely cheap and unfair (never-ending homing projectiles, infinite {{Mook}} respawns of [[DemonicSpiders Chimera]]), locks out all other ninpo spells other than "True Inferno" and forces players to grind the ki gauge in order to build it up to unleash True Inferno on the boss, as it's the ''only'' attack that will damage it to allow the next phase of the fight to occur. The first phase more or less forces players to resort to overusing the cheapest techniques available in order to pass it.
* ThatOneLevel
** The infamous 6-2 in the first NES game: 6-1 and 6-3 are extremely difficult as well, but 6-2 takes the cake for cheap deaths and one spot where players have to exploit a flaw in the programming to get past it. If players die even once on any of the [[SequentialBoss three final bosses]], they're forced to redo the ''entire stage at 6-1 again''.

** The "Path of Zarkhan" chapter in the modern ''Ninja Gaiden'': not that it's particularly harder than previous chapters, but players spend most of the level swimming back and forth to solve a puzzle. Upon solving that, they must go through a long swimming sequence through areas previously visited but now submerged. ''Sigma'' may have removed the puzzle and made the level more straight-forward, but the chapter favors swimming shenanigans over action sequences.
** The ElevatorActionSequence in ''Sigma II'' for Rachel's chapter, mainly because of CameraScrew issues and also because of [[DropTheHammer Rachel's melee weapon]] not being very adaptable to fight in narrow spaces. Savvy players will stand in the corner to charge up the Ultimate Technique over and over again between waves to cheese their way past the lower difficulties, but it gets complicated at higher difficulties where the upgraded flare-based Fiends are DemonicSpiders and deal a lot of damage - often {{One Hit Kill}}s in Master Ninja. Furthermore, a fully-charged Ultimate Technique is no longer a guaranteed OneHitKill on Master Ninja difficulty.
** Ayane's chapter in ''Sigma II'' is the hardest one to beat, particularly at higher difficulties, since she's the "[[FragileSpeedster fast, but weak]]" character of the playable girls and the chapter sends a grab-bag of every enemy type in the game, even those which seem better-designed for heavier, more-powerful weapons. Prepare to see the "GameOver" screen a lot with her.
* TheyChangedItNowItSucks: What some fans think of ''Ninja Gaiden III'', from [[ItsTheSameNowItSucks the game-play not changing much since its predecessors]], to [[ItsEasySoItSucks its tone-downed difficulty]] to [[ItsShortSoItSucks overall game length]] compared to the others. It stands to reason ''Razor's Edge'' was made to correct every criticism inflicted upon ''III''.

* BrokenBase: ''Sigma II'' - some consider it inferior to ''Ninja Gaiden II'' because of the lack of gore, easier difficulty and the removal of puzzles, but others consider it superior thanks to more balanced stage designs, less cheap AI, frame-rate fixes and the removal/revision of the most tedious passages of the original, as well as additional content of playable characters and game modes. The drastically reduced number of enemies and the introduction of a semi-automatic aim for the bow can be seen as a good ''or'' bad thing depending on who is asked.

*** ''Ninja Gaiden III'' as a whole is so {{Main/Anvilicious}} about its “Feel their pain” message that it crosses the line straight into unintentional hilarity.

* PlayerPunch: ''Ninja Gaiden III'' goes to great length to make players feel the pain of the enemies they kill, be it the brutal Steel-on-Bone mechanic or the moaning of enemies if they aren't finished off as they crawl helplessly on the ground, bleeding to death.

* CaptainObviousReveal:
** Turns out [[EvilUncle Murai]], who ''in his very first scene'' talked about how much of a shame it was that the [[ArtifactOfDoom Dark Dragon Blade]] wasn’t being used and whose men can be found dead all over Tairon with [[ApocalypticLog journals that pretty much say he sent them there]], was the bad guy all along! [[SarcasmMode Who could have seen that coming]]?
** ''Ninja Gaiden'' as a whole is notorious for this: seemingly friendly characters that turn out to be villains in “twists” that have ludicrously heavy amounts of {{Main/Foreshadowing}}: the aforementioned Murai, Foster and Clancy from the original Ninja Gaiden NES trilogy, Cliff Higgins from ''III'', Professor Bucky-Wise from the OVA, and Alaricio del Gonzo from ''Yaiba''.

** In the first game of the modern trilogy, especially at the highest difficulties, a good portion of the non-human {{Mook}}s turn into this, such as the black "[[FrickinLaserBeams laser]] [[EyeBeams eye-firing]]" fiends or the feline-based fiends, thanks to their agility and lightning-fast attacks, especially when fought in groups.

*** ''The Ancient Ship of Doom'': [[TheManBehindTheMan H.P. Clancy]] is an assistant to CIA agent A. Foster and the hidden true villain of the game. After hero Ryu Hayabusa slew the evil wizard Jaquio and a demon he summoned, the demon's destruction created a portal to another dimension that is releasing energy. Foster takes over what is left of Jaquio's fortress in the Amazon and renames it Castle Rock Fortress. Clancy and Foster begin to use the other-dimensional energy to [[EvilutionaryBiologist perform experiments]], setting up a lab to create nightmarish creatures called Bio-Noids. When Ryu's girlfriend, CIA agent Irene Lew, was investigating the lab, Clancy has a Bio-Noid that looks like Ryu seemingly kills Irene and then [[FrameUp frames]] Ryu for her murder. After Ryu investigates the lab, Clancy approaches him and appears friendly, [[TreacherousQuestGiver directing him]] to go to the Castle Rock Fortress, saying he cannot condone Foster's experiments. When Ryu confronts Foster, Clancy reveals his true intentions, he will go into the dimensional portal and claim the energy for himself. When Ryu later confronts Clancy in the portal, Clancy reveals his master plan to use an ancient alien warship to [[KillAllHumans destroy humanity]] and replace them with Bio-Noid creatures.