List of unreleased Sonic the Hedgehog video games

The following is a list of unreleased games from the Sonic the Hedgehog series by Sega; most of these games went unreleased due to being cancelled, but there are some that were cancelled for other reasons.

Sonic's Edusoft (1991)
Sonic's Edusoft is a 1991 educational video game featuring Sonic the Hedgehog and developed for the Sega Master System; it was developed by Tiertex Studios at the request of publisher U.S. Gold, however it went unreleased due to Sega revoking U.S. Gold's Sonic license thanks to disagreements, which also lead to the cancellation of planned Amiga and Atari ST ports of the original. The game remained in obscurity until September 2006 when one of the developers made a Wikipedia article about it, although it has since been deleted for lack of references.

On April 27, 2008, the near-final ROM was dumped online, though a hacked version is required since it otherwise won't load on most emulators.

SegaSonic Bros. (1992)
SegaSonic Bros. is a falling block puzzle game featuring three differently colored Sonics in falling pieces of four. Similar to Tetris, the player is able to rotate the blocks, although to make the blocks disappear a Sonic must be surrounded by Sonics of the same color; upon reaching level 30, a white Sonic is added in for extra difficulty; a multiplayer mode is also available where the player who gets to 300,000 points first win.

The game was scheduled to be released in 1992 in Japan, but a failed location test prevented it from being released; in 2016, arcade collector ShouTime revealed he had a working board, and it was released online in July 2018. Interestingly, one of the songs used for the game would be recycled as the Blue Spheres theme in Sonic the Hedgehog 3 and Sonic & Knuckles.

Sonic the Hedgehog and Sonic the Hedgehog 2 (Sega CD, 1992)
Before development on Sonic the Hedgehog CD began, the developers originally intended on porting the original Sonic the Hedgehog and, at one point, its sequel to the Sega CD. The only known footage from Sonic 1 CD comes from the 1992 Winter Consumer Electronics Show. Its was soon decided that there should be a new original title for the Sega CD to take advantage of its hardware.

Treasure Tails (1993)
Treasure Tails was a planned Tails-centric spin-off game proposed by Bill Dunn; the only known mock ups, which were released by Sonic 2 zone artist Craig Stitt in August 2020, shows that it would've been an isometric puzzle game featuring Tails in some sort of ancient ruins. Two Tails-centric games, Tails' Skypatrol and Tails Adventure, were released for the Sega Game Gear in 1995.

Sister Sonic (1993)
Sister Sonic was a planned localization of the Japanese role playing game (RPG) Popful Mail for the Sega Genesis; the localization would've featured the main character replaced with Sonic's sister, and other characters being replaced with Sonic characters. It was later cancelled due to angry letters from fans of the PC version, though a Sega CD port was later released with the original title and characters intact.

Sonic the Hedgehog 3 Limited Edition (1994)
Sonic the Hedgehog 3 Limited Edition (also known as Sonic 3+ and Sonic 3C) is an unreleased compilation game featuring Sonic the Hedgehog 3 and Sonic & Knuckles, which would've combined both games into one, which were the original plans before time constraints forced both games to be split into two; the game was referenced in Famitsu, SEGA Magazine and Mean Machines Sega, although it went unreleased for unknown reasons.

Two ROM images dated April 8 and May 17, 1994 respectively, were released during the February 23, 2008 prototype release by Hidden Palace.

Sonic Jr. (1994)
Sonic Jr. is a educational video game planned for release on the Sega Pico in 1994; it would've starred a younger version of Sonic, similar to Ecco Jr.; nothing is known about the actual gameplay, though it likely never got past the drawing board.

Sonic Sports (1995)
Sonic Sports is a sports game that was in developed for the Sega 32X in 1995; the game was stated by Game Players in March 1995 to be similar to Acme All-Stars, and would've featured Sonic, Tails and Ristar.

Sonic X-treme (1996)
Sonic X-treme is a 1996 3D platform game developed by Sega Technical Institute (STI); originally intended for the Sega 32X under the title Sonic Mars, X-treme was later moved to the Sega Saturn and PC to improve performance and to take advantage of the newer hardware. Despite this, the game went through severe development hell due to issues getting the fish eye lens at 30 FPS on the Saturn, issues with the "boss" engine (which was also used for Nights Into Dreams...), and an unfavourable visitor from Sega of Japan; after Chris Coffin and Chris Senn both became sick from working too hard, Mike Wallis ultimately cancelled the project. Sega initially stated that X-treme would be delayed, but in early 1997 announced its cancellation.

The cancellation of X-treme has been cited by various critics as one of the reasons the Sega Saturn had disappointing sales outside of Japan. A planned film meant to advertise Sonic X-treme was also cancelled. In its place a port for Sonic 3D Blast by Traveller's Tales was released instead to mixed reviews, though it was generally cited as an improvement over the Genesis version. The next mainline Sonic game, Sonic Adventure, would be handled by the original Japanese staff.

Sonic Saturn (1996)
Alongside X-treme, STI was also developing another Sonic game for the Sega Saturn titled Sonic Saturn; designed by Peter Worawiec, Yuji Naka supposedly didn't like this engine, and the game was ultimately scrapped; the developers originally thought of using it for the Special Stages in the aforementioned Saturn version of 3D Blast, however the final uses a Sonic 2 Special Stage-style.

Sonic Extreme (2003)
Sonic Extreme, not to be confused with the previously mentioned X-treme was a skateboarding tech demo created by Vision Scape Interactive for the Xbox in May 2003; it was never announced publicly, though a prototype surfaced in April 2011 from an Xbox development kit. The tech demo features Sonic and Shadow riding on boards through a single level; it's believed that Extreme was the inspiration for Sonic Riders in 2006. In a May 2017 episode of Did You Know Gaming?, four former Vision Scape employees were interviewed about the demo.

When the tech demo hit the internet, several critics expressed their relief that it wasn't developed any further.

Sonic X: Chaos Emerald Chaos (2004)
Sonic X: Chaos Emerald Chaos was a planned second Game Boy Advance video developed and published by Majesco; it would've contained the Sonic X episodes Missile Wrist Rampage and Chaos Emerald Chaos.

Sonic DS (2004)
Sonic DS is a 2004 tech demo created by Sega for E3 2004 as a demonstration for the newly revealed Nintendo DS; in the demo the player slides left and right to make Sonic move faster, and jumping can be done by tapping the top screen, with the goal being to get the highest score. DS was likely always meant to be a tech demo, as the first actual game published by Sega for the Nintendo DS was Feel the Magic: XY/XX; some assets would later be reused for Sonic Rush in 2005, also for the DS.

Sonic the Hedgehog (Nintendo Wii/PC, 2006)
Released for the Xbox 360 and PlayStation 3, Sonic the Hedgehog 2006 (more commonly known as  '06) had two planned versions for the Nintendo Wii and PC that were meant to be released at around the same time; the Wii version was scrapped since Sega decided it would take too long for it to be developed (which eventually lead to the development of Sonic and the Secret Rings), while the PC version was scrapped due to the game being rushed.

Sonic the Hedgehog: Awakening (2006)
Sonic the Hedgehog: Awakening is a 2006 game that was only mentioned on Pete Capella's resume, who was the former voice actor of Silver the Hedgehog from 2006 to 2009; nothing else is known about the game, though it's speculated to have been related to the aforementioned 2006 game.; due to this, many assume the game was cancelled due to  '06 's poor reception.

 

Sonic Riders (Game Boy Advance, 2006)
Sonic Riders is a 2006 racing video game published for the GameCube, PlayStation 2 and Xbox; another version, intended to be an Out-Run-style game, was planned for release on the Game Boy Advance, however it was ultimately cancelled since Sega of Japan wanted more 3D in the game, and time constraints.

Sonic Unleashed (PC, 2008)
A PC version for the 2008 game Sonic Unleashed was planned to be released, presumably based on the Xbox 360 and PlayStation 3 releases of the game; it was never announced, although leftover images in Sonic Generations are presumed to have been intended for use during the install process.

Sonic Generations (PlayStation Portable, 2011)
Alongside the game being released for the PlayStation 3, Xbox 360 and Nintendo 3DS, a version of Sonic Generations was planned to be released for the PlayStation Portable and was going to be based on the 3DS release; for whatever reason, this release was scrapped, although a damaged disc was recovered from a bin using the working title Anniversary.

Sonic the Hedgehog 3 & Knuckles (iOS/Android, 2014)
After the completion of the 2013 remakes of the original Sonic the Hedgehog and Sonic the Hedgehog 2, developers Christian Whitehead and Simon Thomley (known online under the aliases "The Taxman" and "Stealth") created a proof-of-concept remake of Sonic the Hedgehog 3 & Knuckles to the iOS and Android devices in 2014. The game was never greenlit by Sega despite the success of the Sonic CD, Sonic 1 and Sonic 2 remakes; many people believe it might be due to legal issues reguarding Sonic 3 's soundtrack.