Slipped by the NES Censor

Nintendo had a reputation of being a tough censor in the days of the NES and SNES before the establishment of ratings boards.  In these eras, the big-N implemented a modern day version of the Hays Code.  Who needed a video games rating system when every game has been vigorously inspected and cleansed to make it appropriate for children?  Nintendo controlled all licensed cartridge production, and if it did not approve a game then it would not be produced.  (It is a myth that Nintendo manufactured all cartridges, there are PCBs and chips in licensed US cartridges made by Konami, Sunsoft, Namco, Acclaim and Virgin Games).

Maniac Mansion is the best example of how Nintendo would control the approval process.  It required developers to send a prototype cartridge and a text dump.  Any objectionable content would be noted and sent to the company to fix.  Often, developers and publishers would engage in self-censorship to speed the approval process along.

References to sexual activity and nudity were not allowed.  Graphic, life-like violence was also forbidden. Language was to avoid words like "hell", "damn", "crap" and no stronger expletives were allowed.  Over time, Nintendo became more strict about what it would allow on its system.  Most of these examples given below were from the earlier years of the NES's development.

Nintendo of Europe was even more strict on violence.  Germany has long video games on its List of Media Harmful to Young People, the BPjM.  River Raid for the Atari 2600 was the first game on that list and it stayed there until 2002, so Nintendo games had to be very circumspect when it came to depicting any kind of realistic violence.  Thus games like Contra were given a sprite overhaul, replacing all human-like characters with robots and released a Probotector in Europe.  Unfortunately, because of the German standards, all of Europe suffered from this type of lowest common demonimator censorship.

Eventually, Nintendo's strict censorship began to work against it.  When Mortal Kombat for the Sega Genesis, which had the blood and graphic fatalities unlockable with a code, drastically outsold the SNES version, Nintendo began to realize the value of the ratings system.  Both companies and their eventual competitors submitted to the ESRB.  The sales for Mortal Kombat II, which was not censored, were better than the Genesis version.

Bionic Commando

At the end of the game, you must destroy the helicopter of the main villain of the game, "Master-D".  Master D's portrait had a death animation that was very graphic for the time.

Also, Master D's facial features obviously resemble Adolf Hitler's.  This is intentional because the original Japanese game, title : Hitler no Fukkatsu: Top Secret, made explicit that Hitler was the main villain.  While Capcom removed visual and textual references to the Nazi Party in the U.S. version, they kept Hitler's portrait unaltered.  Years later, when Wolfenstein 3D was ported to the SNES, not only were all Nazi references removed, but the posters found on the walls of Hitler were adjusted to reduce the resemblance to the Fürher.

Master-D also calls the hero a "damn fool" for challenging him, and "damn" is a Bad Word which shouldn't have made it into the U.S. release, but it did.

Castlevania

Level 3 of Castlevania features nude statutes in the background.  They may have been harder to notice on small TVs back running the NES video through an RF input back in the day, but the graphics were not changed.  By the time Konami ported Castlevania III to the U.S., the nude statute graphics were changed, but there were more examples of nudity in that game.

Eventually Nintendo would get around to removing crosses in the SNES era, but in the NES era, crosses were not particularly objectionable. All three Castlevania NES games have them, as does Zelda II: The Adventure of Link.

Castlevania II: Simon's Quest

We have the use of "Hell" in this game, right in the introductory text that scrolls if you do not press start at the title screen.

Golgo 13

The censor must have been asleep when this game was approved!  On at least two occasions during the game, Golgo 13 sleeps with female operatives he meets during the game.  He goes up to their hotel rooms after making prior arrangements, suggestive words are spoken, an animation shows the two coming together from their window, the lights go black and all your health is regained.  The voyeuristic view of the latter portion of the sequence only highlights the inappropriateness of this sequence by Nintendo's guidelines.   The Japanese version shows the ladies actually take their clothes off, showing toplessness.

In addition, this game is rather graphic when killing enemies in a first-person view.  When you shoot enemies, blood spurts from their heads.  This happens in the sniping sequences and the maze sequences.  At one point, you smoke a cigarette to regain health.  What kind of message did that send to the kids?

The enemy organization in the US version is called DREK, but in the Japanese original they are clearly identified as Nazis.  The file you obtain in the Greece Maze has a Swastika in the Japanese version and the true enemy is a cyborg version of Adolf Hitler, not "Smirk".  The US version keeps Hitler's likeness for "Smirk".

The sequel The Mafat Conspiracy: Golgo 13, is much more tame but does feature Golgo 13 smoking in the cutscenes and plenty of violence with Ninja Gaiden like cutscenes.

Kid Icarus

The statutes in world 4-1 are topless, as is the illustration of the Syren enemy in the game's manual.

The Legend of Zelda

The third Dungeon in the first quest is called "Manji" and the rooms are in the shape of a swastika.  This followed the Buddhist usage and faces counter-clockwise, not the Nazi usage which is usually clockwise and angled at 45 degrees.  The swastika had been in use in Japan for over one thousand years before Hitler appropriated it.

However, the counter clockwise version of the swastika was used by the Nazis, perhaps most notably as part of the standard for the 1st SS-Panzer Division Leibstandarte [bodyguard] SS Adolf Hitler after the fall of France.  No one complained about the use of the symbol at the time The Legend of Zelda was released apparently.  A decade later, parents did complain when the symbol was found on Pokemon cards and Nintendo announced that it would no longer use the symbol on Pokemon cards it released to the United States (and probably Europe) because of the negative cultural connotations.

Also, Link's shield and the Darknut shields have crosses on them.  Nintendo let religious symbols like crosses by in the early days.  

Magic of Scherezade

The boss of the second world, Curly, has obvious breasts.  "Curly" should really have been "Kali", the Hindu goddess of death, who is typically depicted topless and with six arms, which Curly's second form has.

Maniac Mansion

Although this game was heavily censored to remove objectionable content, Razor or Sid can explode Weird Ed's hamster by putting it in the microwave in the U.S. version.  Nintendo got wise to this and this act of animal cruelty was no longer possible when the game was later released in Europe.

Here is the original article "The Expurgation of Maniac Mansion", which describes what was left out and what was later removed from the game :

http://www.crockford.com/wrrrld/maniac.html

Metal Gear

In Metal Gear, cigarettes as a usable item, helpful when trying to beat the timed sequence at the end of the game where you must escape the building after beating the final boss before a bomb blows it up.  Smoking is bad, but in the NES era it was not high on the censor's priorities.  This would eventually changed as demonstrated by the cigarette item being changed to "fogger" in Metal Gear Solid for the Game Boy Color. The item still looks like a cigarette.

Ninja Gaiden

Ninja Gaiden has a rare use of the verb "to kill" when Foster is discussing the death of Dr. Smith.  Use of the verb "to kill" or any of its conjugations was strongly discouraged in the NES era.  In RPGs, a character is never "killed", usually they "died", were "slain" or "perished".  A party may be "annihilated".  This went to goofy levels when Final Fantasy II/IV's U.S. SNES release used the word "swooned".

Also, in Jaquio's lair and on his chest you can see six-sided stars, better recognized as a Star of David. During the NES and SNES era, Stars of David were frequently removed from RPGs like Final Fantasy and Final Fantasy II/IV, where they alluded to mystical abilities.  These were altered or removed for the Ninja Gaiden Trilogy release.

Ninja Gaiden II: The Dark Sword of Chaos

Similar to Ninja Gaiden, Jaquio has a pentagram (instead of a hexagram, maybe he lost a point because he died) on his chest.  This was altered for the Ninja Gaiden Trilogy. When you defeat Jaquio, his blood touches the Dark Sword of Chaos, transforming him into a demon.  The blood was turned from red to green in the Ninja Gaiden Trilogy.

Rambo

At the beginning of the game, Colonel Trautman tells Rambo : "You've got 36 hours to get in, complete your assignment, and get the hell out."  H-E-Double hockey sticks was a big no-no thereafter.

Ring King

Ring King has become particularly infamous for its in-between round animation of the corner men.  When looking at the animation, it is hard to find a non-obscene explanation.  The animation is not quite as suggestive in the arcade original.

I was too lazy to make an animated GIF, but there are no intervening frames.

River City Ransom

River City Ransom has a spa area where your character can recover his stamina.  The game shows you showering in Pop's Health Club, and among the graphics is a shot of your character toweling off his bare backside.  They show a dimpled butt.

Sqoon

Sqoon has a topless mermaid enemy, which appears on the title screen and later in the game.  This would not have gone unnoticed during a later period.

Taboo: The Sixth Sense

Taboo was practically unique in the NES library because it advertised on the box that it is not intended for children under fourteen.  Taboo is a tarot card reading simulator.  You input your name, date of birth and your gender, ask a question and the game will deal ten tarot cards and give you its interpretation of them. Among the cards that can be revealed are The Lovers, which shows rear male nudity and nearly-nude female nudity.  After it reads the cards, it will give you some "Lucky Numbers", asking you to select your state of residence.  The name/birthdate/gender screen has a cross and a pentagram.

This is a RareWare game, and I would suggest that only Rare's close relationship with Nintendo allowed them to publish this simulator.  Divination, occultism and fortune telling is offensive to Biblical Christianity.