In a 2011 interview with the game's developer Masaaki Nagaura published in STG Gameside #5, Nagaura was asked at what points did he struggle when porting the game from mobile phones to the PC? He responded:
"From the start I had planned to release it for PC and mobile phones, so there weren’t any particular difficulties. When developing a game, the graphics are always expensive to create, but once you start thinking about improving their quality there’s really no end to it, and I always struggle with where to draw the line. But since I started development on the mobile platform, which has hardware limitations, I knew what the minimum requirements were beforehand. From there I brushed things up for the PC version, and I think it was a really efficient way to develop. With the mobile version my goal was to make “the best shooting game ever for a mobile phone,” so I worked hard tuning it up."
Despite Floigan Bros. being initially developed prior to the Dreamcast's release in 1999 (of which the main characters Moigle and Hoigle made cameos in the Dreamcast advertising campaign "It's Thinking"), and then-President of SEGA's American division Bernie Stolar saying that "Floigan will do for SEGA what Mario did for Nintendo", the game would go through developmental setbacks until finally releasing on July 30, 2001, months after SEGA ceased production on SEGA Dreamcast.
Because of this late release window, several pieces of monthly on-disc DLC for the game, as well as the concept of exchanging Moigles through the Dreamcast VMU, were left on the cutting room floor.
On December 24, 2022, an anonymous user on the Internet Archive uploaded the source code for Rayman 4, the original prototype for what would later become Rayman Raving Rabbids. The Rayman 4 prototype, which was known to be a 3D Platform game with beat'em up elements that involved the Rabbids as the game's antagonists, showcases several interesting features. Some of the content featured in the E3 2006 trailer can be found in the prototype such as rideable animal companions, interchangeable costumes, combat gameplay, and explorable settings such as a forest, cave, & gear temple.
Some newer never-before-seen content includes: • Early unfinished cutscenes some featuring a witch doctor from Rayman 3: Hoodlum Havoc. • Explorable Rabbid bases/lairs with programmed Rabbid enemies. • Rayman utilizing several projectile weapons. • Other explorable worlds such as a village setting and a sphincter-inspired level. • Rayman controlling Rabbid vehicles such as a hovercraft and large robots. • When receiving damage, Rayman loses his clothing except for a leaf covering. This costume was repurposed as the Rayomz skin in Rayman Legends seven years later.
M.U.G.E.N was originally intended as an engine for shooting games, however, it was changed to a fighting game engine due to a low amount of quality fighting games being available on PC at the time.
Hajime Tabata worked on The 3rd Birthday and Final Fantasy Type-0 at the same time, both games having originally been intended for mobile devices, but were later changed to PlayStation Portable games. Square Enix requested Tabata to focus on The 3rd Birthday, which almost lead to Final Fantasy Type-0 being cancelled.
The original plan for the game was a PvP, online MMO game known as Fate/Apocrypha. However, these plans were cancelled early in development. The project was later revived as "Fate Online Project Reboot" on the behest of publisher Aniplex wanting to make a mobile game to promote the Fate IP. According to head writer Kinoko Nasu, he never owned a smartphone prior to the development of Fate/Grand Order, but got one and played various free-to-play mobile games for reference. Fate/Apocrypha itself would later be revived as a Light Novel series.
El Tigre: The Adventures of Manny Rivera was intended to be developed over a span of 12 months. However, due to the cartoon being abruptly cancelled the game was developed over 2 months instead, with a greatly reduced budget, and a planned Wii version being cancelled.
A PlayStation version of the game was being developed by The Code Monkeys, but was cancelled in favor of a PlayStation 2 version. When asked why, the Neopets team revealed that they "felt that it couldn't achieve everything we wanted it to on the PS1", but also noted that "the graphics will be much better."
In August 2023, several days following a controversy, Phisnom announced that he had been terminated from the Fazbear Fanverse Initiative and would no longer be developing Five Nights at Freddy's Plus. Prior to this, he had been banned from the game's Steam forums and removed as a developer. The day after he announced his removal, the game's Steam page was removed from the public, and on November 10th, all videos and posts related to the game on both Twitter and YouTube were made private, leading to the belief that the game had been cancelled entirely.
On September 17, 2023, the official Dark Deception: Monsters & Mortals Twitter account revealed that there were plans for a crossover DLC pack based on the game Murder House by Puppet Combo, but that said plans fell through for unknown reasons. A pitch trailer for the collaboration was also uploaded as part of the tweet.
Dutch electronics company Philips planned to release a Donkey Kong game for the CD-i as part of the deal with Nintendo that led to the release of Hotel Mario, Link: The Faces of Evil, Zelda: The Wand of Gamelon, and Zelda's Adventure. The Donkey Kong game's existence was alluded to in two "Gaming Gossip" articles by Electronic Gaming Monthly as well as a trade ad which depicted Donkey Kong exiting a limousine alongside Mario, Link, and Zelda. However, more concrete evidence for the game's existence didn't emerge until former Riedel Software Productions employee Adrian Jackson-Jones included a post on his LinkedIn page stating that he programmed the engine for it (the LinkedIn post incorrectly cites Australian visual effects studio Rising Sun Pictures due to them sharing initials). This information was then brought to public attention in 2022 by the LostMediaWiki, a website which documents searches for lost or otherwise publicly unavailable works.
An investigation by Time Extension led to writer John Szczepaniak getting in contact with both Jackson-Jones and Riedel Software Productions owner Michael J. Riedel. Both parties have little memory of the Donkey Kong game due to the amount of time that passed and the company's habit of erasing their data for cancelled projects. Additionally, Jackson-Jones revealed that due to a memory disorder, he recalls little about the game other than his direct experiences programming it. Despite this, Jackson-Jones was able to confirm his involvement with the Donkey Kong game, stating that one of the biggest difficulties during development was the CD-i's memory limitations, which were circumvented by only loading in assets that would be visible on-screen, using the player's movement to determine what to put into memory.
Sonic Mars was a concept game that was cancelled for unknown reasons (though it likely had something to do with the limitations and ultimate failure of the Sega 32X), before eventually being reworked into what eventually became Sonic X-treme.
In 2007, two different scripts were leaked for the cancelled game. The first, written by Michael Kosaka, focused on the 3D graphics and notably included elements from the 1993 Sonic the Hedgehog television series (referred to by fans as "Sonic SatAM"), which was airing at the time. The second, written by Don Goddard, focused more on how the game combined 3D graphics with 2D sprites, and dropped the SatAM elements.
SimCopter 64 was a game announced by Maxis at E3 1997 which was meant to be a complimentary game to the later announced SimCity 64. It underwent a tumultuous development cycle that saw it change from a simple rescue mission game into something entirely different. There were also conflicting reports from both Nintendo and Maxis about what console it would be releasing on and the level of connectivity it would share with its counterpart SimCity 64. All of these issues ultimately ended in it fading out of the public eye and being silently cancelled as no more updates were given leading up to its supposed release window.
There was a game by the name of Cabbage which was to be developed and released for the Nintendo 64DD, an expansion peripheral for the Nintendo 64. The project was helmed by Shigesato Itoi, creator of the Mother series, with other big name developers eventually being added on to help finish the project. Even with this help it would never see the light of day. It was said by Shigeru Miyamoto that, "the conversations and design techniques that popped up when we were making Cabbage are, of course, connected to Nintendogs and other things that we're doing now." Those "other things" most likely referring to Animal Crossing as it used many of the base elements said to have been made for Cabbage including the internal clock feature of the N64DD. To this day there are no known screenshots, videos, or demos of this cancelled game.
At Spaceworld 2000, Shigeru Miyamoto showed off a tech demo for a project he had been working on for a number of years known as Mario 128. This project had a tumultuous development cycle with little to no details coming out over the years until finally in 2007 at a GDC Keynote he revealed what came of this laborious project. He explained that some parts of the project were used to make Pikmin and other parts of the project were utilized in Super Mario Galaxy.
According to illustrator Greg Hardin's resume, a Nintendo DS version of the game may have been planned at some point, only to be cancelled. It is unknown if it would have been based on the PS2 or GBA version of the game.
During the game's development, Lucas - the protagonist of Mother 3 - was briefly considered as a replacement for Ness by the development team. However, due to the delays surrounding Mother 3's original Nintendo 64 release (and that game's eventual cancellation), Ness returned instead - as was originally planned.
Both Ness and Lucas would go on to be playable in this game's sequel, Super Smash Bros. Brawl, though Lucas's appearance would be based on Mother 3's eventual Game Boy Advance release as opposed to what is now commonly referred to in the fan community as "EarthBound 64".
Inside the files of the Wii version of Wacky Races: Crash & Dash is a file depicting the title of an unreleased game called Carmageddon: 4 Ever, seemingly implying that the game was built off of an unreleased build for the cancelled Carmageddon 4 that was also being developed at Edios during the 2000s.
Dutch electronics company Philips planned to release a Donkey Kong game for the CD-i as part of the deal with Nintendo that led to the release of Hotel Mario, Link: The Faces of Evil, Zelda: The Wand of Gamelon, and Zelda's Adventure. The Donkey Kong game's existence was alluded to in two "Gaming Gossip" articles by Electronic Gaming Monthly as well as a trade ad which depicted Donkey Kong exiting a limousine alongside Mario, Link, and Zelda. However, more concrete evidence for the game's existence didn't emerge until former Riedel Software Productions employee Adrian Jackson-Jones included a post on his LinkedIn page stating that he programmed the engine for it (the LinkedIn post incorrectly cites Australian visual effects studio Rising Sun Pictures due to them sharing initials). This information was then brought to public attention in 2022 by the LostMediaWiki, a website which documents searches for lost or otherwise publicly unavailable works.
Bubsy 3D contains an unused copyright screen for a Japanese release, licensed to Coconuts Japan.
Inside the files of the Wii version of Wacky Races: Crash & Dash is a file depicting the title of an unreleased game called Carmageddon: 4 Ever, seemingly implying that the game was built off of an unreleased build for the cancelled Carmageddon 4 that was also being developed at Edios during the 2000s.