Sonic the Hedgehog is a video game series and media franchise created and published by the Japanese company Sega. Since the release of the original Sonic the Hedgehog for the Sega Genesis in 1991, several Sonic games have been canceled or reworked into other projects. Builds of unreleased Sonic games have leaked online, and some introduced concepts that were reincorporated in released games.
Early in Sonic history, two spin-off games—the edutainment game Sonic's Edusoft and the falling block puzzle game SegaSonic Bros.—were completed, but Sega declined to publish them. Sega and Nihon Falcom planned to remake Falcom's PC-8801 game Popful Mail (1991) for the Sega CD as a Sonic game, but canceled it in favor of a more faithful remake after a negative fan response. Unreleased Genesis Sonic games include three spin-offs pitched by Sega Technical Institute (STI) and Sonic Crackers, which was reworked into the 32X game Knuckles' Chaotix (1995).
STI began working on Sonic X-treme, planned as the first Sonic 3D platformer and the first Sonic game for the Sega Saturn, after the release of Sonic & Knuckles (1994). Development was hindered by company politics, problems adapting Sonic to 3D, and crunch. After two lead developers became ill, Sega canceled X-treme and released a Saturn port of the Genesis game Sonic 3D Blast (1996) in its place. The cancellation is considered an important factor in the Saturn's commercial failure, as it left the console with no original Sonic platform game.
After Sega exited the video game console market to become a third-party developer, plans to develop a sequel to Sonic Adventure 2 (2001) were canceled twice, first in favor of Sonic Heroes (2003) and later in favor of Sonic Unleashed (2008). Other unreleased Sonic games include the skateboarding game Sonic Extreme, which may have served as the basis for Sonic Riders (2006), and proposed follow-ups to Sonic Chronicles: The Dark Brotherhood (2008), Sonic the Hedgehog 4: Episode II (2012), and Sonic Mania (2017).
Early projects Sonic's Edusoft
Sonic's Edusoft, the first game in Sega's Sonic the Hedgehog franchise developed outside Japan, was developed by the British studio Tiertex Design Studios for the Master System in 1991. The edutainment game comprised minigames that players accessed from an isometric hub world. The minigames included math and spelling questions; three were non-educational. Edusoft was virtually finished and Tiertex conducted focus testing at a Didsbury school. It would have been published by U.S. Gold, but Sega was uninterested in licensing the project.
Information about Edusoft surfaced when one of its programmers wrote a Wikipedia page about it. The page was deleted after editors deemed it a hoax, so he emailed screenshots to Sonic fansites, but the online Sonic community also deemed it a hoax. By 2010, the ROM image had leaked online and its authenticity was verified.
Home computer game During the development of Sonic the Hedgehog (1991) for the Sega Genesis, U.S. Gold acquired the license to develop versions for home computers, including the Amiga, Amstrad CPC, Atari ST, Commodore 64, and ZX Spectrum. The computer versions were planned for release in 1992, but Sega revoked the license following Sonic the Hedgehog success to keep the franchise exclusive to its platforms. The Italian magazine The Games Machine published screenshots purportedly from the Amiga version alongside its review of Sonic the Hedgehog, though Games That Weren't wrote they appeared to have been mockups created in Deluxe Paint.
SegaSonic Bros. SegaSonic Bros. was part of a series of arcade games that Sega commissioned after the success of Sonic the Hedgehog. It was a falling block puzzle game designed by the Taito alumnus Fukio Mitsuji, who created the Bubble Bobble series, and featured multicolored Sonics as the blocks. It ran on the Sega System C2, an arcade board based on the Genesis hardware. Although SegaSonic Bros. was complete, Sega decided against a wide release after it performed poorly in late 1992 location tests. Some of its music was recycled in later projects; Sega rearranged the main theme for the Sega CD port of Teddy Boy Blues (1985) and reused one of the gameplay tracks as the special stage theme in Sonic the Hedgehog 3 (1994).
SegaSonic Bros. was considered lost for many years, but a working board was discovered in 2016 and the ROM image was leaked in 2018. Reviewing the leaked ROM, Hardcore Gaming 101 wrote that it was "easy to see why" SegaSonic Bros. was canceled, with complicated rules, needlessly difficult gameplay, and jumbled, cheap-looking visuals. They felt that falling-block puzzle games such as Taito's Cleopatra Fortune (1996) better executed its design elements.
Console ports Sega planned to port Sonic the Hedgehog and Sonic the Hedgehog 2 (1992) to the Sega CD, a CD-based add-on for the Genesis. Sega showcased the Sonic the Hedgehog port at Summer CES in 1992. The ports were canceled in favor of an original game, Sonic CD (1993). A Master System port of the Game Gear game Sonic the Hedgehog: Triple Trouble (1994) was also planned, but it ultimately remained a Game Gear exclusive.
Sister Sonic
Sister Sonic was a remake of Popful Mail (1991), an action role-playing game developed by Nihon Falcom for the PC-8801. It was developed for the Sega CD by Sega Falcom, a joint venture between Sega and Nihon Falcom. Sister Sonic replaced Popful Mail characters with those from the Sonic franchise, with the protagonist, Mail, recast as Sonic's female relative. It would have been the first Sonic role-playing video game, predating Sonic Chronicles: The Dark Brotherhood (2008).
Sega Falcom's director, Kazutaka Yano, announced Sister Sonic in the November 1992 issue of the Japanese magazine Beep, Beep! MegaDrive. In response, Popful Mail fans launched a letter-writing campaign urging Sega to remove the Sonic connections in favor of a more faithful remake. By November 1993, Sega had decided to release the game as Popful Mail in Japan and turn Sister Sonic into its Western localization. For unknown reasons, this did not come to fruition, and Working Designs released a faithful localization of Popful Mail in the US in 1995.
Sega Genesis Treasure Tails In February 1993, Sega Technical Institute (STI) pitched the spin-off Treasure Tails, an isometric puzzle-platform game for the Genesis that starred Sonic's sidekick Miles "Tails" Prower. In 2020, the STI artist Craig Stitt shared mockup screenshots he created for the pitch on Facebook after discovering them in a 1995 video resume.
Astropede Stitt pitched Astropede, a spin-off starring a caterpillar-like character, that Sega of America executives approved. He worked with another developer, Ken Rose, to create a playable build for the Genesis that reused graphics from a deleted Sonic 2 level, but development never progressed further. Gameplay footage surfaced in 2020.
Sonic-16 Roger Hector, the head of STI, wanted to develop a game based on the Saturday morning Sonic the Hedgehog cartoon (1993–1994), and took STI developers to DiC Animation's studios in Burbank, California after the release of Sonic Spinball (1993) to demonstrate his idea. The STI developer Peter Morawiec began designing Sonic-16, a side-scrolling video game for the Genesis with more focus on story than previous Sonic games. Morawiec and STI's art director, John Duggan, created a demo in under a week using Brilliance software. The demo featured slow gameplay due to the difficulty of animating fast backgrounds with Brilliance, though Morawiec planned to include speed-based sequences.
Sega management was not interested in a spin-off and felt the idea was too slow for Sonic, and Sonic co-creator Yuji Naka disliked its design, so Morawiec worked on Comix Zone (1995) instead. In 2007, Morawiec said that canceling Sonic-16 "was probably the right decision", as the Sonic franchise was still in its infancy and would have been harmed by too many spin-offs. He noted the Sonic cartoon had not even aired yet when Sonic-16 was pitched. Some gameplay elements later surfaced in Sonic X-treme.
Sonic Crackers / Sonic Stadium
Sonic Crackers, also known as Sonic Stadium (the title on the ROM image header), was a platform game for the Genesis developed by a Japanese Sega team in 1994. It was intended as the last Genesis Sonic game and to succeed Sonic & Knuckles (1994). Most of the team had never worked on a Sonic game before, aside from a producer and some artists who contributed to Sonic CD. The name likely comes from clackers, a toy comprising two balls connected by string. Sega presented Crackers to video game journalists in secret showings, but canceled and reworked it into Knuckles' Chaotix (1995), a spin-off starring Knuckles the Echidna for the 32X add-on.
A ROM image, compiled at some time in 1994, was leaked online by a Belgian hacking group in June 1995. It features Sonic and Tails joined by an elastic band of energy and is split between two side-scrolling and two isometric top-down levels. The levels appear to be early versions of two Chaotix areas. Kotaku and Retro Gamer described Crackers as a proof-of-concept or game engine test, as it features broken collision, unpolished physics, and no enemies. According to the author Ken Horowitz, Sega canceled Crackers in response to a downturn in the 16-bit market as next-generation hardware was approaching.
By December 1994, Crackers had been reworked into Chaotix, which retains the tethering mechanic, music, and some visual elements but removes Sonic and Tails, the top-down levels, and the art. Horowitz wrote that the top-down levels instead served as the basis for Sonic 3D Blast (1996). Some fans speculated that the Crackers ROM was an April Fools' Day hoax due to one reading of its build date, but its authenticity was corroborated by references in an internal Sega design document, leftover sprites in a prototype build of Yu Yu Hakusho Makyō Tōitsusen (1994), and text found in a leaked Knuckles' Chaotix prototype. A cartridge version was auctioned for $146.50 in 2001.
Sega Saturn and Dreamcast Sonic X-treme
Described by Nintendo Life as "arguably the most famous unreleased Sonic game", Sonic X-treme was developed by STI from 1994 until its cancellation in 1996. It would have been the first Sonic 3D platformer, predating the Dreamcast game Sonic Adventure (1998), and the first Sonic game for the Sega Saturn. The story went through several iterations; the one described in promotional materials involved Tiara Boobowski and her father, Professor Gazebo Boobowski, calling on Sonic to help defend the six magical Rings of Order from Doctor Eggman. X-treme featured a fisheye camera system and levels that rotated around a fixed center of gravity, meaning Sonic could run up walls and arrive at what was previously the ceiling. Like previous Sonic games, X-treme emphasized speed and physics, and featured special stages and collectible rings.
STI began developing X-treme as a side-scrolling Genesis game to succeed Sonic & Knuckles. They shifted to the 32X and then the Saturn and Windows, and the game was scheduled to be released during the 1996 holiday shopping season. Development was hindered by disputes between Sega of America and Japan, Naka's reported refusal to let STI use development tools from Sonic Team's game Nights into Dreams (1996), and problems adapting Sonic to 3D. The developers worked under crunch conditions, to the point that one programmer moved into STI's offices to work 20-hour days. By August 1996, two lead developers became severely ill, making meeting the deadline impossible, and the producer Mike Wallis canceled X-treme. In its place, Sega released a Saturn port of the Genesis game Sonic 3D Blast as the holiday Sonic game. A Saturn test build leaked in 2007, gameplay footage surfaced in 2008, and playable builds for the Saturn and Windows leaked in 2015.