In 2013, a Kingdom Hearts online mobile game was in development that never saw the light of day. It was to be called "Kingdom Hearts: Fragmented Keys". The game was rumored to feature customizable avatar characters (like Union Cross). It would also have been in 3D instead of Union cross' 2D art style. Most interesting and exciting of all though (gathered from concept art no less) was the Disney world list as the game would feature returning worlds like: Agrabah, Wonderland, a Lilo & Stitch Hawaii world, Space Paranoids/The Grid, London/Neverland, and Dwarf Woodlands. It also included worlds that didn't appear in the series yet but would appear in later games like Union Cross and Kingdom Hearts III, such as: Arendell (Frozen), Kingdom of Corona (Tangled), and Niceland/Game Central Station (Wreck-It Ralph). Finally, and most shockingly, a world based on the Star Wars franchise, although this world's chronology is unknown as concept art show different conflicting eras, such as an image of characters Anakin, Obi-wan, Padme, and Master Yoda in their exact looks from Star Wars: The Clone Wars movie and series in a separatist gunship's hanger as well as a planet that looks similar to Tatooine and an anachronistic Death Star power station room. It is unknown why this game was cancelled.
During the height of Super Mario 64 DS' popularity, a popular rumor was that Waluigi was hidden as an unlockable character - this rumor was inspired both by the presence of Wario and Luigi without their combined counterpart, and a set of coincidences within the game and its supplementary material:
• The character switching room having 4 doors, one for Mario; one for Luigi; and one for Wario, along with a final, empty room (this room actually contained a Power Star). • 4 bunnies existing in the game: a yellow bunny who appears when playing as Yoshi, a pink bunny who appears when playing as Mario, a green bunny who appears when playing as Luigi, and an orange bunny who appears when playing as Wario. The manual's page on the mini-games that bunnies are used to unlock shows a purple bunny that doesn't appear in the game. • The title screen and floor of the Rec Room having a colour scheme based on yellow (Wario's color), green (Luigi and Yoshi's color), red (Mario's color), and purple (Waluigi's color). • The image of Peach's Castle on the file select screen having what appears to be an open window that does not exist in the game, which many assume is where Waluigi would be hiding.
The popularity of these theories would birth an infamous hoax known as "Purple Prizes", a graphic created by Andrew Brown of Nintendo World Report in an attempt to rebirth the mystery he felt as a child from trying to find Luigi in the original Super Mario 64 for the younger Nintendo DS generation, and posted it to DeviantArt and a set of gaming forums under the false pretense of being a scan from an unnamed magazine. Although he clarified that the picture was fake a mere 2 days later, the image still spread online like wildfire, and was misreported as originating from Nintendo Power or IGN. Brown noted that some attempts to debunk flaws in the image were not based on the actual and plentiful flaws he acknowledged the image as having, but rather misconceptions such as Waluigi's yellow gamma being a C or accusing certain images of being based on the original Nintendo 64 game instead of the DS remake.
In Mrs. Puff's sprite sheet for SpongeBob Saves the Day!, an image can be found of an unnerving semi-realistic CGI character, internally called "Yummer". The character's unsettling design, combined with an image present in the code of Sandy's torn-up scuba suit, caused a lot of speculation about the image's potentially macabre origin. The original creator of the graphic eventually came forward and revealed that the character was simply a developer in-joke from the late 2000s used as a placeholder for a scrapped feature where an undecided character would peek from the back of one of the Krusty Krab's poles. The character's name is also not "Yummer", but rather simply "Yum", named as such because "that's the opposite of what you'd use to describe him". The torn Sandy suit was part of a puzzle where SpongeBob would need to wear one of the treedome's helmets.
When Tsuyoshi Tozak, director of Bubble Bobble 4 Friends, was asked about if Bub and Bob would appear in the Super Smash Bros. franchise, they simply responded "let's skip that question". The interviewer theorized that they may have been under a non-disclosure agreement, citing a similar response when asking Studio MDHR, the developers of Cuphead, about if they wanted to make an animated series based on their game, which did eventually happen. However, come the end of Super Smash Bros. Ultimate's DLC cycle, a Bubble Bobble multimedia adaptation did not happen in any form, suggesting that Tozak was likely indifferent on the possibility rather than under NDA.
Many fans and critics have noted similarities between the aesthetic of Pizza Tower and "off-model" 1990s cartoons such as Ed, Edd, n' Eddy and The Ren & Stimpy Show. Game creator McPig has claimed not to be a fan of those series and to have not been influenced by them, although he did still take influence from the more cleanly-drawn SpongeBob SquarePants, and an unclear inspiration from 1990s cartoons would still be cited on the game's Steam store page description.
The Coolmath Games website has often been noted for a severe lack in mathematics-related content. The title of the website was often theorized to have been chosen in order to bypass school browser filters, but that is not the case. It was instead named that to act as a spin-off of the Coolmath website, which was math-themed.
Infamously, the ending cutscene of Banjo-Tooie has series antagonist Gruntilda threaten "Just you wait until Banjo-Threeie!". Contrary to popular belief, the lead designer for the Banjo series, Gregg Mayles has stated on Twitter that a direct sequel to Tooie was never planned for development, and that the supposed "tease" was merely a joke, playing on how the word "Threeie" would be unpronounceable in British English.
In the first, second and sixth SoulCalibur games, the classic numeric input for Ivy's notoriously difficult Summon Suffering throw is 376231A+G (Attack + Guard). This number combination actually holds significance as it appears to be a reference to the former phone number for Namco's headquarters from before they were acquired by Bandai, being 03-3756-2311.
Allegedly, the developers used the phone number as the basis for the input as a reaction to an in-joke among Tekken and Soul Edge arcade communities, who would react to degenerate or weird stuff in the games with "gonna call Namco about this". The joke being: "If you can't do the throw, go call Namco about it." However, since this input was brought back in SoulCalibur VI long after the phone number stopped being used by Bandai Namco, this adds an additional (albeit probably unintended) layer to the joke: "Go call Namco about it. Oh wait, you can't."
In the 2023 film "The Super Mario Bros. Movie", the Japanese name for the character Spike (the foreman from Wrecking Crew) was changed in the corresponding dub. Although no specific reason was given as to why the change was made, it can be assumed it was done to avoid controversy as the character's original Japanese name is "Blackie", which is also a derogatory racial slur in English-speaking countries used to refer to dark-skinned people of African descent.
Nightmare in Dream Land was the last game to credit Shinichi Shimomura, who co-directed the game with series creator Masahiro Sakurai, as a staff member. Shimomura previously served as a regular map designer for the Kirby series and directed Kirby's Dream Land 2, Kirby's Dream Land 3, and Kirby 64: The Crystal Shards. Exactly what became of Shimomura after Nightmare in Dream Land is unknown, with many fans speculating that he retired from the video game industry and/or passed away.
A secret message can be found on the title screen of the NES version of the game with the use of two controllers. At the title screen, select "CONSTRUCTION" on the menu. Press Start on Controller 1 to enter the mode, then press it again to return back to the title screen. Repeat this seven times. After the seventh enter-and-exit, hold Down on Controller 1 and press A eight times on Controller 2. Then, hold Right on Controller 1 and press B twelve times on Controller 2. Finally, press Start on Controller 1 to activate the message featuring an animation of a green droplet falling.
"THIS PROGRAM WAS WRITTEN BY OPEN-REACH WHO LOVES NORIKO ....."
The most likely person as to the identity of "Open-Reach" is Tomcat System's founder and programmer Ryoichi Ookubo because of the similarities between "Reach" and "Ryoichi". It should be also noted that his name is hidden twice in the game's ROM, and from one fact pointed out by a Russian LiveJournal user, that the name Open-Reach appears as "OPR" on the title screen of another game Tomcat System developed, the 1991 Famicom game Castle Quest published by Hudson Soft.
As for Noriko, her identity remains unknown. In the comments section of the sourced video, one commenter claimed that Noriko was Ookubo's daughter who was three years old at the time of the game's development, while the aforementioned LiveJournal user claimed that Noriko was a romantic partner, claiming her to be a former Namco graphic designer named Noriko Ikegawa (whose name would later appear in the credits for the Nintendo game Animal Crossing as a model designer), but there is no known substantial evidence to support either of these claims.
A prototype version of this game contained an item, called "Flametrail", which is not present in the final release of the game. It is theorised this item would use the jet engines of the ship as a means of damaging other ships.
In the January 1993 interview with game's programmer Yuji Naka published in the Beep! magazine, he stated that the rumors about Tails being a girl or Sonic's girlfriend wasn't true, he was always intended to be a boy from the very beginning. He also stated that Tails' name was originally Miles for most of the game's development. His nickname first came up from during a meeting with a producer from ABC.
It is possible to unlock an alternate ending sequence featuring Yogurt. The requirements to unlock this ending are unknown, but an unsubstantiated claim on a fan forum suggests it could be tied to unlocking the alternate bikini outfits which are only in the Japanese version of the game.
A game with the same title was originally planned to release on the DS. In 2005, IGN got hold of an official internal Nintendo software list that revealed a number of key DS games set to be announced in the future. All of the games on the list were eventually announced and released except for one project simply titled "Metroid Dread". However, the title quickly disappeared from Nintendo's title plan lists and in magazine articles before that year's E3.
A game tentatively titled "Bomberman" was originally planned for release on the Nintendo 3DS in 2011. From what little footage and screenshots exist of the game, it appeared to have similar gameplay to Bomberman 64, while also being one of the only games in the series to have Bomberman use a health bar instead of health stock. The game would have centered around Bomberman as he tries to save Central City from a robotics corporation, while possibly getting turned into a robot himself as implied by the game's tentative box art. It would have also had a Battle Mode similar to previous entries in the series that was rumored to be compatible with future Bomberman games for the 3DS should those have been made.
The game was announced in an overview trailer released in February of 2011 showcasing games for the 3DS that would release later that year, but was cancelled the following month due to the closure and acquisition of Hudson Soft by Konami.
According to the August 1994 issue of magazine Mean Machines Sega, a Doctor Who game for the Mega Drive / Genesis was in development by SEGA around the time Steven Spielberg was involved in working on the show, but nothing else was known about this.
Revealed in concept art by former Retro Studios employee Sammy Hall, Retro Studios actually worked on two major projects for Nintendo using two of their biggest IPs before Nintendo cancelled them for unknown reasons.
One of them was a project in the Mario series centered around the supporting character Boo. Little is known about the project outside of the Concept art, but hints released with the concept art tease that it would have been released for one of Nintendo's handhelds (such as the DS) as well as there being things in the game referred to as "possession powers" and "Broomies".
The other game, rumored to be centered around the character of Sheik from The Legend of Zelda series, was more elaborate. Hints leaked by Hall and released with the concept art suggest that it would of been about, and centered around, the origin of the Master Sword in the Bad Timeline and would feature "the last Sheik" as it's main character. The game would have also seen the Dark Gerudo tribe engaging in their decade-long birth to Ganon. The project was describe as an "Action/RPG".
The development of the first Donkey Kong game was outsourced by Nintendo to Ikegami Tsushinki, a company who is believed but not confirmed to have previously worked with Nintendo on several of their early ventures into arcade games. They produced and sold to Nintendo somewhere between 8,000 and 20,000 printed circuit boards for Donkey Kong, and it is believed that Nintendo went on to copy an additional 80,000 boards from this batch without Ikegami's permission. Despite the sale, because no formal contract was known to have been signed between the two companies, Ikegami owned the source code to Donkey Kong as they had created it, and never sent it over to Nintendo.
In order to create a sequel on the coattails of the success of the first game, Nintendo employed subcontractor Iwasaki Giken to reverse-engineer Donkey Kong so Nintendo’s staff could develop the game's sequel, Donkey Kong Jr. Should this narrative be verifiably true, this would make Donkey Kong Jr. Nintendo's first "in-house" video game created by themselves without any assistance from outside development companies. Ikegami viewed this use of the source code as blatant copyright infringement, and sued Nintendo in 1983 for ¥580,000,000 (around $91,935,800). A trial in 1990 ruled that Nintendo did not own the source code to the original Donkey Kong, and the parties settled out of court the same year for an undisclosed amount.
The game faced controversy around its release, as it was reported that Ubisoft initially recalled copies of the game in the UK due to a line that was considered offensive. Ubisoft refuted this however, stating the title wasn't being recalled. The game was later re-released in the UK with a PEGI 12 rating.
In 2013, a Kingdom Hearts online mobile game was in development that never saw the light of day. It was to be called "Kingdom Hearts: Fragmented Keys". The game was rumored to feature customizable avatar characters (like Union Cross). It would also have been in 3D instead of Union cross' 2D art style. Most interesting and exciting of all though (gathered from concept art no less) was the Disney world list as the game would feature returning worlds like: Agrabah, Wonderland, a Lilo & Stitch Hawaii world, Space Paranoids/The Grid, London/Neverland, and Dwarf Woodlands. It also included worlds that didn't appear in the series yet but would appear in later games like Union Cross and Kingdom Hearts III, such as: Arendell (Frozen), Kingdom of Corona (Tangled), and Niceland/Game Central Station (Wreck-It Ralph). Finally, and most shockingly, a world based on the Star Wars franchise, although this world's chronology is unknown as concept art show different conflicting eras, such as an image of characters Anakin, Obi-wan, Padme, and Master Yoda in their exact looks from Star Wars: The Clone Wars movie and series in a separatist gunship's hanger as well as a planet that looks similar to Tatooine and an anachronistic Death Star power station room. It is unknown why this game was cancelled.
During the height of Super Mario 64 DS' popularity, a popular rumor was that Waluigi was hidden as an unlockable character - this rumor was inspired both by the presence of Wario and Luigi without their combined counterpart, and a set of coincidences within the game and its supplementary material:
In Mrs. Puff's sprite sheet for SpongeBob Saves the Day!, an image can be found of an unnerving semi-realistic CGI character, internally called "Yummer". The character's unsettling design, combined with an image present in the code of Sandy's torn-up scuba suit, caused a lot of speculation about the image's potentially macabre origin. The original creator of the graphic eventually came forward and revealed that the character was simply a developer in-joke from the late 2000s used as a placeholder for a scrapped feature where an undecided character would peek from the back of one of the Krusty Krab's poles. The character's name is also not "Yummer", but rather simply "Yum", named as such because "that's the opposite of what you'd use to describe him". The torn Sandy suit was part of a puzzle where SpongeBob would need to wear one of the treedome's helmets.
Nightmare in Dream Land was the last game to credit Shinichi Shimomura, who co-directed the game with series creator Masahiro Sakurai, as a staff member. Shimomura previously served as a regular map designer for the Kirby series and directed Kirby's Dream Land 2, Kirby's Dream Land 3, and Kirby 64: The Crystal Shards. Exactly what became of Shimomura after Nightmare in Dream Land is unknown, with many fans speculating that he retired from the video game industry and/or passed away.
A secret message can be found on the title screen of the NES version of the game with the use of two controllers. At the title screen, select "CONSTRUCTION" on the menu. Press Start on Controller 1 to enter the mode, then press it again to return back to the title screen. Repeat this seven times. After the seventh enter-and-exit, hold Down on Controller 1 and press A eight times on Controller 2. Then, hold Right on Controller 1 and press B twelve times on Controller 2. Finally, press Start on Controller 1 to activate the message featuring an animation of a green droplet falling. 
A prototype version of this game contained an item, called "Flametrail", which is not present in the final release of the game. It is theorised this item would use the jet engines of the ship as a means of damaging other ships.
A game tentatively titled "Bomberman" was originally planned for release on the Nintendo 3DS in 2011. From what little footage and screenshots exist of the game, it appeared to have similar gameplay to Bomberman 64, while also being one of the only games in the series to have Bomberman use a health bar instead of health stock. The game would have centered around Bomberman as he tries to save Central City from a robotics corporation, while possibly getting turned into a robot himself as implied by the game's tentative box art. It would have also had a Battle Mode similar to previous entries in the series that was rumored to be compatible with future Bomberman games for the 3DS should those have been made.
According to the August 1994 issue of magazine Mean Machines Sega, a Doctor Who game for the Mega Drive / Genesis was in development by SEGA around the time Steven Spielberg was involved in working on the show, but nothing else was known about this.
Revealed in concept art by former Retro Studios employee Sammy Hall, Retro Studios actually worked on two major projects for Nintendo using two of their biggest IPs before Nintendo cancelled them for unknown reasons.
