This was originally posted to the Port Saiid forums by Dire 51:

In the PCE Dracula X, there's a spot onboard the pirate ship that only Maria can get to. After you get the 1up from the engine block, you can go over the top of it and you'll see a small passageway in the wall on the left. Use Maria's "temper tantrum" slide to work your way through it, and you'll come out on the other side of the wall. Go up and you'll be in a small room with what looks like some kind of mirror/portal. I have no idea what to do in this room, if anything, and I've never seen anything about it mentioned on any CV site.

Screenshot of the area beyond the engine block with the hidden door, taken from VGmaps.com

Crawl responded:

Yeah, I've been there, and I stood in front of that rectangle and pressed "up" (assuming it was a door a la SMB2), but nothing happened. There are some other parts on the pirate ship that had me wondering - it looked like was it was just barely impossible to climb up some of the masts, and I wondered if you timed it right with regard to the boat's undulating movement if you could reach it. But now I'm guessing 'no'.

While the book's pretty much been closed on the Stop n Swop mysteries (the ice key and the eggs), there are still a couple of things that bother me about this game. The first is the unlockable treasure chest in the bedroom of Mad Monster Mansion. Though there was an egg in the wine cellar and one in the bathroom, nothing ever came of this chest. Why do game developers put treasure chests in games that you can't open? Don't they know it will drive us nuts? (See also Shadowgate below for another unlockable chest.)

Screenshot taken from this YouTube video by inbouniyoukoso

You'll likely recognize this scene from B-K's infamous "Game Over" sequence. Near the end of the game, you'll be able to walk into this room and see the machinery for yourself. You will also notice the locked doors with the grublin-head doorknockers on them that can never be opened. Nintendo Power's official strategy guide for this game included a screenshot of this room where the telepod machinery was gone and one of the doors was clearly standing open. Two things that bother me the most in videogames are treasure chests that can't be opened and doors that can't be opened, and B-K has both! It's even worse when the strategy guide hints at the possibility of it opening, but alas, there is probably nothing there.

There are several overhead areas in Level 4 of Blaster Master where there are powerups on islands that you cannot reach. This leads me to believe that it was planned at one time for Jason to be able to jump in the overhead areas as well as the sidescrolling areas, but that feature was taken out. The funny thing is that it was planned at least as far as Level 4 before they got rid of it, if that's the case. (Thanks to CodieKitty for this mystery.)

Special buildings in Breath of Fire, such as shops and inns, have a sign outside that marks what kind of business they are. The game contains one, and only one, building with a beermug sign, indicating that it is a bar. The bar exists in the town of Nanai, near the beginning of the game, but normally you could never enter it. You cannot enter the town during the day because soldiers immediately throw you out, and at night, a sleeping soldier blocks the bar's door.

But by hacking your way into Nanai during daytime, you can enter the bar and find a rather unfinished room with people whose dialogue is clearly intended for a barroom setting. The bar even has its own theme music that is not heard anywhere else in the entire game.

The question is... why was this put in here at all? I probably would have guessed that NOA may have wanted the bars censored out of the game, but you'd think there'd be more than one if that's the case, and that this one would at least look finished since it was put in near the beginning (not to mention that the beermug icon is still there and clearly visible).

On your way to Dracula's Castle at the end of the game, there's a staircase you have to go down to pass through the final town before you get the castle's bridge. Instead of taking that staircase, keep going straight and you'll eventually end up in a swampy area with a vibrant green color scheme not used anywhere else in the game. There is nothing of significance to this area at all - no items, clues, or characters to talk to. However, there is an invisible staircase at the end between the ground and the row of platforms. It is the only invisible staircase in the whole game. Why this area was put here at all is a total mystery since there is no reason to ever go here.

After you defeat the Vampire and have to escape the mansion, there's this one part where a bunch of zombies are gathered around a villager. They will kill him if you wait too long, but you can save the villager by killing the zombies first. The villager will then run away. Follow him and keep your eyes on him - He runs outside the mansion...and jumps headfirst into a bottomless pit! Why on earth does he commit suicide after he's been saved?

There doesn't appear to be any significance to this, either...There's no benefit for saving him and no penalty for letting him get killed.

PAVGN informs me that this same villager exists on the Conker: Live & Reloaded Xbox remake and he does the same thing. But there is still no significance to saving him.

This mysterious room and pillar in the Creepy Castle Museum was the source of much lost sleep for gamers in the N64's heyday, trying to figure out what purpose it could possibly serve. My personal guess is that the pillar is just there to decorate the room and make it look more "museum-like", and/or to give a boost up for Tiny to reach a Banana Balloon (though it is not necessary since she can hit it from the floor, too).

The Level 7 Ghost Ship is the only dungeon in the game that is missing a room, 07-02. They are numbered 07-00, 07-01, and go right to 07-03. Although the room was found via hacking, it is empty with no entrance and no escape. It is unknown why the room was never completed and what its original purpose was.

After you find Cyan in the World of Ruin on top of Mt. Zozo, there will be a treasure chest up there that you can open to receive a "Simple Book on Machinery" and a "Book of Secrets". These have no known purpose. The implication seems to be that Cyan was secretly studying the machinery book to overcome his fear of machines, but it doesn't outwardly affect anything. And the "Book of Secrets" is a total mystery...

In all my years of playing video games, this is still the strangest, most inexplicable and mysterious boss I have ever seen. When you get to the end of Level 3 on the NES version of the game, you will find a giant dead body sitting at a desk. Destroy the body with grenades, then throw grenades at the desk's shadow to open up the stairway to the final level.

There's nothing that explains this anywhere in the game or the manual, so I tried coming up with my own explanation - and the only thing I could figure is that maybe you were supposed to fight this guy as the final boss, but the surprise is that he's already dead, so you need to find the true leader of the "evil army" by unearthing the hidden 4th stage.

Screenshot from vgmuseum.com

But then things get weirder when you look at the original arcade version. Here, the boss is not sitting at a desk. It's rested against a barricade instead, and there is no fourth stage after you destroy it. Once it's gone, you move past the barricade and rescue General Kawasaki. Even weirder is that there's a Swastika on the floor in front of it, which can be seen in this YouTube video by dangorou147.

Even the Atari 2600 version has it.

They must have considered it to be one of the most important elements of the game to bother trying to reproduce it on the Atari 2600. It's funny because if you didn't see it in another version of the game, you'd probably have no idea that's what it even is. It looks like a guy with a giant lightbulb for a head who's rather disappointed to see you.

This arcade flyer from The Arcade Flyer Archive, pointed out to me by Super Galvatron, implies that we should be "surprised" by what we find at the end, but still doesn't explain it. Hmm...

In a Nintendo Power interview, developer Sam Deasy said that the Blackwing boss fight was his favorite in the game. Blackwing's name can also be found in the ROM alongside all the other bosses' names. However, no fight with this boss actually exists in the completed game. The questions are... Does any trace of him still exist anywhere in the ROM? Where was he supposed to be placed in the game? And why was he taken out?

There is indeed a refrigerator with a padlock on it in a jail cell near the very end of Reggie's Castle Ruins, right before you fight the boss.

It bounces around a lot, but as far as I can tell, there is no way to get to it or open it. Viewing the gamedata file in Notepad reveals all of the game's dialogue and there doesn't appear to be any dialogue for a talking celery anywhere (unless it is compressed and doesn't show up in Notepad).

I first heard about this one a lonnnng time ago, way back on the N-Sider forums at Nintendo.com circa 1997-1998 or so. Someone on the Super NES BBS was claiming to have seen "ghosts" in Misery Mire. He even said that sometimes he could see something strange when the lightning flashes (before the storm is cleared up). I personally have never seen anything and don't know whether that was just a rumor or a glitch I haven't yet encountered, but there is definitely something weird going on in here. When you have the duck and the Titan's Mitt, go to #6 on the Light World map, lift the rock to your right, and step on the warp to enter Misery Mire.

   

Use the Bombos Medallion anywhere nearby (the lilypad/stump thing I'm sitting on in the above picture is a good place to try it). You should notice that something unseen catches fire...

...and it may leave behind a bomb.

While many theories had arisen as to what these invisible enemies are, it seems that they are Cyclops Fish (aka Dark World Zoras) that have been spawned in the wrong spot so that they can't surface. Usually these types of enemies surface in deep water, spit a fireball, then submerge. But for whatever reason, these ones are spawned under shallow water and can't do anything.

It is reminiscent of the Howler that spawns in a group of trees and the Bomb Bee that spawns in a wall high up off the screen in Secret of Mana. Much like those cases, it is probably just a programming error that didn't get caught before it was released.

   

One day, while messing around with a glitch, I managed to get the game to display an unused dungeon tile from the Skull Woods Dungeon. They ended up replacing any large 4 x 4 tiled statue-like structures, such as the thrones in Hyrule Castle, the Rocklops Statues in the Dark Palace, and the statues of Ganon in Ganon's Tower. This is one of many examples of unused graphics buried deep within game ROMs that, for whatever reason, is not used in the final project.

The Desert Palace is the only other dungeon in the game that doesn't have any 4 x 4 statues, but I viewed a Desert Palace save state in Vsnes and it revealed a Rocklops Statue stored in memroy, even though they aren't used there. This suggests that the Skull Statue is not just a memory filler and was definitely intended for specific use in Skull Woods Dungeon. Why it was omitted is unknown.

During the part of the ending sequence where the faces of characters you've met from all throughout the game are briefly flashed on-screen, there are two that appear that do not exist anywhere in the game at all, as far as I could tell. They are a crying monkey with green hair and a clown-like being with long ears. Who these characters are and what they were intended for, nobody knows. I may never have even noticed them except that I was experimenting with a program that captures animated gifs from emulators and thought that was a good sequence to use it on. Imagine my surprise when these showed up in the results.

Might and Magic (at least the NES version if not others) appears to have several items with no known use. One such item is a 10 Foot Pole, which you often win from enemies and it can even be bought at a shop, but I have never figured out a use for it. I mean, a 10 Foot Pole? It seems like a joke item, but why have it for sale in a shop?

Other weird things you can get are a Jade Amulet that appears to do absolutely nothing, a Bag of Garbage with a curse on it (!!), and a Bag of Sand. Some items' only purpose is to be sold for a lot of money, but none of these things even get you that much.

Also, in the Quivering Forest Dungeon, there's a face inset in a wall that says, "I would pay highly for a green-handled, pearl-encrusted Abelnuski."

No such item as an "Abelnuski" appears in the game, although that may not be too surprising as this line of dialogue sounds like a joke. However, the real mystery is what even is an "Abelnuski"? Searching the word on the internet only brings up sites mentioning this dialogue in Might & Magic and nothing else.

This is a really weird case of censorship if there ever was one. Wait long enough at the title screen of Monster Party and eventually you will see the Shrimp, Onion Ring, and Shishkebob bosses slide on by.

But look carefully and you'll notice something very odd... there is a red substance dripping from each of these bosses. It is either blood or ketchup. My guess is that since they are food monsters, it's supposed to be ketchup that looks like blood.

   

The really weird part is that when you get to these bosses in the actual game, that red substance is not there!

(Yes, I was playing a Spanish ROM, but it's the same on the English version)

Now, under normal circumstances, I'd wager that Nintendo censored the blood for the bosses, but missed it on the opening sequence because whoever was in charge of the censorship didn't wait long enough for them appear and thus didn't see them there.

However, why censor it at all when this type of imagery, present in the game, was much more obvious and allowed:

   

And in these cases, there's no doubt about that being blood, whereas the "blood" on the food bosses could just be ketchup. Makes no sense...

In the original Red, Blue, and Yellow versions of Pokemon, there was a truck on the docks near the SS Anne that was normally not within range of vision. But if you got a Pokemon with Surf ability before the SS Anne departed, you could surf over to the docks on the right and find the mysteriously hidden truck. This spawned all sorts of rumors, most involving moving the truck to find the elusive Mew. These rumors all proved to be false and the reason for the truck's existence has remained a mystery. (Thanks to James FP for this mystery.)

According to Strawberry Eggs a Lava Cookie can be found hidden near the truck in the Fire Red and Leaf Green remakes.

When you reach the point in the game where you learn how to make a Weather device, make one and go to the Old House on the Quintenix overworld map. Enter it and use the Weather anywhere on the screen with the Old House ruins. The screen will darken and it will start to rain. Talk to the man who's walking around there and he will give you "Scrap B".

To this day, I have never found a use for Scrap B and no online FAQ mentions any known use for it either.

The large spinning circular thing on the world map near Empire Northtown still remains unidentified to this day. The strongest theory on this object is that it was something that was cut from the game, possibly when it was reduced from the (canceled) SNES CD format to the cartridge format.

The unreachable door in the Resistance Headquarters is another conundrum. Though we were able to prove the door is just background and cannot be entered, the question remains as to why it was placed there at all. My theory is that the Resistance HQ may have originally been planned to be more "hidden" than it actually is, and you'd possibly have to find a way to this door to get to it, but eh, I don't know that for a fact.

In the room with the Wraith where you get the Cloak, there is a door in the upper right part of your radar map. It is up so high, that you cannot see it on the screen. If you try to move there, a message tells you that it's too high for you to reach. There is no way to ever reach this door. Why put a door there that you not only can't reach, but you can't even see it?

   

On the same subject, I've always been perplexed by the door in the room with the well. I'm not sure why this door is here since there's no way to open it. When I first played this game many years ago, I got stuck near the end and tried everything under the sun to open that door to no avail. Another room contains a doorway on a high ledge with cold air rushing out of it. If you try to get to it, the ledge breaks. There is never any way to reach this door.

   

There is also the matter of the mysterious chest in the dragon's room that can never be opened, and the landslide-covered stairway that you will never know where it leads to.

Submitted by PAVGN: In Super Mario Sunshine, Episode 3 of Noki Bay has Mario explore the innards of a bottle in which he has to find eight red coins. At the bottom of the bottle, there are some stone ruins. Inside the the stone ruins are two doors. If you aim the camera correctly, you will see through the door and see a small closed book. The door cannot be opened, and the purpose of the book has never been revealed by Nintendo.

Here is the door you need to look behind.

Aim the camera correctly, and voila!

These screenshots were taken from this YouTube video by NintendoElites

According to that YouTube page, the book was supposed to be an item you needed to retrieve in a beta level that was cut from the final game, so this mystery is somewhat-solved. Still an interesting find, though.