Sonic Synergy (lost original build of "Sonic Boom: Rise of Lyric" Wii U action-adventure game; 2007-2013)
Sonic Synergy was one of the original builds and the original title for the poorly-received 2014 Wii U game Sonic Boom: Rise of Lyric. While the game was spawned independently of the cartoon series to come, they were soon merged into a mass-media production that also included a comic book series, a toy line, clothing, and a new character added to Sonic Team's own roster (Sticks the Badger). The original ideas for the game, however, were very different.
Around 2007, it was stated that SEGA were looking for Western development teams to revitalize their intellectual properties such as Sonic the Hedgehog, Golden Axe, and more. While Golden Axe: Beast Rider came out to bad reviews and low sales, Sonic's western production was forgotten about. Big Red Button, a squadron of ex-Naughty Dog developers, was called on to produce the game. During the earlier part of development, drastic re-designs for the characters were proposed. Sonic Team disapproved of these strange designs and desired they stick closer to the source material.
The game featured a storyline featuring the "Ancients", ancestors of Sonic and company's, who sealed the evil Lyric (an owl, a natural real-life predator of hedgehogs) away. Chao, known as "Chaos", was able to be used in the game. Eggman would have been featured, as a younger, thin, and hillbilly-like character, implying time travel may have been a stronger component of the experience. Originally, the game was developed for PlayStation 4 and Xbox One, and possibly PC, but was moved to Wii U, the first of the game's many production troubles.
As shown via the title screen, a "battle mode" was planned to be incorporated, likely a multiplayer VS. mode. During the game's development, SEGA began their mass-media production of Sonic Boom, and the game was absorbed into it. Lyric was changed to a snake, and elements from the TV series were added. Due to the surprise critical acclaim of Sonic Colors, the tone of the whole franchise steered towards comedy and the original storyline was excised. In addition, Big Red Button had a limited time to crank out the game and the end result was one of the most poorly-received Sonic games ever released, with criticisms going towards the final game's large amount of glitches, dated visuals, and poorly implemented gameplay mechanics.
- Shadow the Hedgehog (lost Teen rated version of platformer; 2005)
- Sister Sonic (lost build of cancelled "Sonic the Hedgehog" localization of "Popful Mail" Sega CD side-scrolling platformer; 1993)
- Sonic 3D Blast (found cassette demo tape of unused game soundtrack; 1996)
- Sonic Adventure New Year's DLC (found "Sonic the Hedgehog" holiday-themed DLC; 1998)
- Sonic Boom (non-existent lost episode of animated TV series; 2014)
- Sonic Boom 2013 (lost Crush 40 livestream performance from "Sonic the Hedgehog" convention; 2013)
- Sonic DS (lost Nintendo DS tech demo; 2004)
- Sonic Generations (lost game demo; 2010)
- Sonic Jr. (lost build of unreleased Sega Pico game; existence unconfirmed; 1994)
- Sonic Riders (lost build of cancelled Game Boy Advance port of racing game; 2006)
- Sonic Saturn (lost build of cancelled Sega Saturn prototype of platformer; mid-1990s)
- Sonic Sports (lost build of cancelled Sega 32X sports game; 1995)
- Sonic The Hedgehog (lost build of cancelled Sega CD port of Sega Genesis platformer; 1992)
- Sonic The Hedgehog 3 & Knuckles (lost build of cancelled iOS port of Sega Genesis platformers; 2014)
- Sonic The Hedgehog: Awakening (lost build of cancelled "Sonic the Hedgehog" game; existence unconfirmed; late 2000s)
- Sonic X-Treme (found build of unreleased Sega Saturn platformer; 1996)
- Sonic at the Olympic Winter Games (found iOS game; 2010)
- Sonic the Hedgehog "2006" (lost complete build of Xbox 360/PlayStation 3 platformer; 2006)
- Sonic the Hedgehog (lost Tokyo Toy Show prototype build of Sega Genesis/Mega Drive platformer; 1990)
- Sonic the Hedgehog (lost Winter Consumer Electronics Show 1991 demo build of Sega Genesis/Mega Drive platformer; 1991)
- Sonic the Hedgehog (lost build of cancelled Amiga port of Sega Genesis platformer; 1992)
- Sonic-16 (lost build of unreleased Sega Genesis/Mega Drive game based on "Sonic the Hedgehog" animated TV series; 1993)
- Sonic Runners (found endless runner mobile game; 2015)