Sonic the Hedgehog (1991 video game)

Gameplay

Sonic the Hedgehog is a platform game where players control the titular character Sonic, who is tasked with defeating Doctor Robotnik and obtaining the six Chaos Emeralds. The game takes place from a side-scrolling perspective. He is capable of running at high speed through levels that include springs, slopes, bottomless pits and vertical loops. The levels are populated with robot enemies, inside which Dr. Eggman has trapped animals; destroying a robot frees the animal, but is not necessary to complete the game. His primary form of offense is a spin attack, in which he curls into a ball and spins his body, damaging enemies and certain obstacles upon collision. This may be performed by jumping or rolling.

Scattered around each level are gold rings that can grant Sonic protection from a single enemy or hazard as well as an extra life if 100 are collected. Also scattered throughout the level are canisters containing power-ups such as additional rings and temporary invincibility. Signposts act as checkpoints where Sonic can respawn after losing a life.

The game is split into six principal zones, followed by a short Final Zone. Each main zone has its own visual style, and while some enemies appear throughout, each zone has unique enemies and obstacles. Each main zone is split into three acts, all of which must be completed. At the end of each main zone's third act, the player confronts Dr. Eggman for a boss fight. For most of the fights, Eggman's vehicle is fitted with different weapons. After completing the sixth zone, the player continues to the single-level Final Zone for a last encounter with Eggman inside a large machine environment. A brief animation shows Sonic's return to the first zone, with animals liberated from Dr. Eggman.

Reaching the end of any zone's Act 1 or Act 2 with 50 rings will cause a large ring to appear through which Sonic can jump to enter a bonus stage. In them, Sonic is continually curled up in his Spin Attack animation, and bounces off the bumpers and walls of a fully rotating maze. In these levels, the player earns a number of continues for each multiple of 50 rings collected, but the main goal is to obtain the Chaos Emerald hidden within the maze. Colliding with any of the blocks marked "GOAL" ends the level.

Plot

In his attempt to steal the six Chaos Emeralds and harness their power, the mad scientist Doctor Eggman has trapped the animal inhabitants of South Island inside aggressive robots and stationary metal capsules. A hedgehog named Sonic aims to thwart Eggman's plans by freeing his animal friends and collecting the emeralds himself. If Sonic collects all the Chaos Emeralds and completes the game, an ending sequence is shown. If all the emeralds are not collected, Eggman taunts the player while juggling any of the Chaos Emeralds not collected by the player in an alternate ending.

Development

Background and character design

In the 1980s, Sega had limited success with Genesis ports of its arcade games, but wanted a stronger foothold against its main competitor, Nintendo. In 1988, Sega of Japan began an in-house competition to create a rival to Nintendo's mascot Mario. For the next three years, programmers and designers at Sega worked on a brand character to rival Mario. In 1990, Sega ordered its in-house development studios to develop a game featuring a mascot for the company. Sega's president Hayao Nakayama wanted a character as iconic as Mickey Mouse.

Conception of Sonic the Hedgehog began in November 1989, when character designer Naoto Ohshima was working on another project titled Twin Stars. The story focused on a pair of twin brothers from the Dream World defending it against the boss of the Nightmare World, "Thirteen." The game was to feature smooth terrain and loops that the characters would run through. While the gameplay concept was approved by Ohshima's superiors, the characters were not, leaving Ohshima to come up with a new protagonist.

The team developed ideas for characters, an engine, and gameplay mechanics. Development emphasized speed, so Sega considered fast creatures such as kangaroos and squirrels and eliminated designs not associated with fast animals. One idea, a rabbit able to grasp objects with prehensile ears, showed promise but was too complex for the Genesis hardware. The team narrowed its search to animals that could roll into a ball, their idea for an attacking move, and considered armadillos and hedgehogs. The hedgehog character, proposed by employee Naoto Ohshima, prevailed. Ohshima went on vacation to New York, taking sketches with him. He went to Central Park and asked locals for their opinions on them, and Sonic was the favorite. A man with a moustache, who eventually became Dr. Robotnik, was in second place.

Sonic was originally teal-colored, then a light shade of blue, but he was changed to dark blue so he would stand out against certain backgrounds and to match the Sega logo. According to Ohshima, Sonic's basic design was created by combining Felix the Cat's head with Mickey Mouse's body. His shoes had buckles through the inspiration of Michael Jackson's boots on the album cover for Bad and the red and white color scheme of Santa Claus, whom Ohshima saw as the most "famous character in the world". Sonic's spikes were emphasized to make him sleeker, and he was given the ability to spin while jumping (so attacking and jumping could be controlled with one button). The new character was originally named "Mr. Hedgehog", but the eight-member team changed his name to "Sonic" and took the nickname Sonic Team. According to Yuji Naka, Sonic Team was a one-time unofficial nickname for the studio within Sega that was used during the development of the game; it was never mentioned again on the division's releases until Ohshima-directed and Naka-produced Nights into Dreams was released in 1996. The name would permanently stay when its successor Sega AM8 was spun off as Sonic Team Co., Ltd. in 2000.

Ohshima said that "Sonic" was chosen because it represented speed. Ideas proposed to flesh out the character included placing him in a rock band, giving him vampire fangs, and giving him a human girlfriend named Madonna. Sega of America scrapped these ideas to keep his identity simple. Sega of America also expressed concerns that most Americans would not know what a hedgehog is. According to Mark Cerny, who worked in Tokyo as an intermediary between the Japanese and American Sega offices, the American staff felt the character was "unsalvageable". They made plans to educate Sonic Team on character design with the work of Will Vinton, the creator of the California Raisins. They proposed a full-scale recreation of the character, but compromised with Sonic Team to simply make design changes for western audiences. The antagonist was named "Dr. Eggman" in Japan and "Dr. Robotnik" in other regions as a result of a dispute between Sega's American and Japanese divisions.

Concept and programming

With a satisfying protagonist established, Sega turned to programmer Yuji Naka, who had impressed executives with his work on Phantasy Star and the Genesis port of Ghouls 'n Ghosts. Naka was a fan of Super Mario Bros. but wanted something faster, so the game was made to play quickly, which was where he focused most of his effort. Production on Sonic the Hedgehog officially began in April 1990 and lasted about 14 months. Naka explained that the reason he wanted a fast game was that he had ported Ghouls 'n Ghosts, and wanted to work on its movement but found it slow.

Sonic the Hedgehog was developed by a team of seven at Sega R&D9: two programmers, two sound engineers, and three designers, People came onto the team as the need for content increased.

Due to the popularity of Mario, Naka wanted Sonic to take over the American market. Sonic's default speed was set to that of Mario while running. Tests were run using the Genesis' tool library, and problems such as flickering, slow frame rates, and shaky animation soon became apparent. Increasing Sonic's speed caused animation problems. Naka solved this by developing an algorithm which retained fluidity. All that was left was to optimize of the game speed to adhere to the staff's expectations. The team noticed that different people had different perceptions of the game's speed: some believed it was too fast, which caused disagreements. As a result, it was slowed down.

The loop running was implemented in a tech demo by Naka, who developed an algorithm allowing a sprite to move smoothly on a curve by determining its position with a dot matrix. Naka's prototype was a platform game with a fast-moving character rolling in a ball through a long, winding tube, and this concept was fleshed out with Ohshima's character designs and levels by Yasuhara. Sonic the Hedgehog was unveiled at the Tokyo Toy Show, held between June 7–10, 1990. At this point, Sonic was only able to "run at high speed on a slightly wavy track." As so little was done at the time, the team wanted to try and "bluff" their way through the demo, making the game look far more polished than it actually was. Yasuhara originally intended to work on the game for three months due to the delay of his planned move to the United States by the outbreak of the Gulf War, but was engrossed in the project for nearly a year. His designs for levels were intended to attract both hardcore and casual gamers by integrating occasional challenging set pieces into mostly accessible level design. The color scheme was influenced by the work of pop artist Eizin Suzuki, and the aesthetics of Green Hill were influenced by the geography of California.

In designing the gameplay, Naka was inspired by Nintendo employee and Mario creator Shigeru Miyamoto, whose games he had enjoyed playing years earlier. Admiring the simplicity of Miyamoto's mechanics in complex environments, Naka decided that Sonic would be controlled with only a directional pad for movement and a single button for jumping. He also wanted his creation to be more action-oriented than the Mario series; while playing Super Mario Bros., he had wondered why the levels could not be cleared more quickly.

Ohshima, Naka and Yasuhara worked 19 hours a day on the project for several months. Due to the need to demonstrate the Genesis' technological prowess, the game underwent extensive testing and redesign, which took over six months. According to Naka, the game had the fastest-ever character speed in a video game and a rotation effect in the bonus stages that had been considered impossible on the console.

The team intended to add a two-player mode displayed via split-screen, but Naka's programming knowledge was insufficient to implement it. A two-player mode appeared in Sonic the Hedgehog 2 (1992), whereby the second player controls Sonic's sidekick Miles "Tails" Prower. Sonic Team also intended to include a sound test with animations of Sonic breakdancing to a band of animal characters, including a crocodile keyboardist who was later introduced into the series as Vector the Crocodile in Knuckles' Chaotix in 1995. The sound test was scrapped for time reasons and Naka used the freed up memory to add the iconic "Se-ga!" chant used in TV commercials as a startup sound.

Naka's relationship with Sega was tenuous during this time, and he received little credit for his work. He left the company shortly after the game's release, although Sega of America hired him later. Before leaving, however, he defied Sega's prohibition of developer credits by displaying a few names in black text on a black background, identifiable only by looking at the code. Naka stated that level design was a major challenge: he created maps much wider than normal and tried to ensure players would not get lost. It took him around eight months to develop Green Hill Zone as he kept restarting from scratch. Naka also stated that the team was trying to create smooth maps, and that implementing looping structures was a challenge because Sonic would break through them instead of running around them. The backgrounds were also a challenge, as the game's speed created the impression of going backwards.

Yasuhara wanted the game to appeal to both Japanese and American players, which was why Green Hill Zone was redesigned many times. Sonic Team wanted the level to portray the character correctly. Its checkered ground was inspired by 3D image rendering from computers, an idea Naka obtained from Sega developer Yu Suzuki, who used this technique with Space Harrier. The team read Famitsu to stay informed of what their rivals were doing so they could avoid their mistakes.

Music

Main article: Music of Sonic the Hedgehog 1 and 2#Sonic the Hedgehog (1991)

Sega director Fujio Minegishi had connections to the music industry and suggested his friend Yūzō Kayama write the Sonic score. However, Sonic Team did not think Kayama's music would fit, and so commissioned Masato Nakamura, bassist and songwriter of the J-pop band Dreams Come True. Nakamura said he was surprised, as he had just started with Dreams Come True, but accepted as he was inspired by the team's desire to outperform Nintendo. He said the hardest part was working with the limited number of sounds that could play concurrently: he was limited to four, and said that his lack of knowledge of music on computers made it "impossible". He wrote the soundtrack concurrently with the Dreams Come True album Million Kisses. After he finished the compositions, they were digitized using an Atari ST and the program Notator.

On October 19, 2011, over 20 years after the release, a three-disc compilation of music from Sonic the Hedgehog and Sonic the Hedgehog 2 was released in Japan. The first disc features original tracks from both games, the second contains Nakamura's demo recordings before they were programmed into the Genesis, and the third has songs by Dreams Come True and their associated Akon remixes.

Packaging and release

Game-package illustrator Akira Watanabe said that his goal was to make the characters "colorful", using clear lines and gradation to "finish them neatly". According to Watanabe, the developers asked him to create a package design "similar to pop art ... without being particular to conventional packages" – something "original" and "stylish". Sonic was not revealed until the January 1991 Winter Consumer Electronics Show because Sega wanted to wait until the right time and because they saw an opportunity to "steal the show". Sonic the Hedgehog was believed to be the most impressive game at the show and won the CES award for innovation.

Sega of America CEO Tom Kalinske wanted reassurance that the character would not fail. The global head of marketing, Al Nilsen, and the senior product manager, Madeleine Schroeder, became involved in redesigning Sonic for American audiences. Artist Greg Wray was commissioned to redesign the character, and a new backstory was created where Sonic was from Nebraska. Sega playtested Sonic across the United States with Mario fans: they were shown Mario and then played Sonic the Hedgehog. 80 percent preferred Sonic the Hedgehog, and the game was shown at the 1991 Summer CES. The game was completed in May 1991, during Japan's Golden Week. It arrived in the United Kingdom on June 21, 1991, widely released in North America on June 23, and in the PAL regions and Japan the following month. In November 1991, Sega of America included Sonic as a pack-in game with American Genesis consoles, replacing Altered Beast. This enabled Sega of America to sell 15 million Genesis units. Genesis owners who bought their consoles before the switch could request free copies of Sonic the Hedgehog by mail. Sega of America created a marketing campaign, making Sonic its new mascot.

Other versions and rereleases

8-bit version

Main article: Sonic the Hedgehog (8-bit video game)

A version of Sonic the Hedgehog was developed by Ancient and released in late 1991 for Sega's 8-bit consoles, the Master System and Game Gear. Its plot and gameplay mechanics are similar to the 16-bit version, though some level themes and digital assets are different and Chaos Emeralds are scattered throughout levels rather than bonus stages. Gameplay as a whole is simplified; the level design is flatter and has a larger focus on exploration, with no vertical loops, and Sonic cannot re-collect his rings after being hit. The game has a different soundtrack composed by Yuzo Koshiro, which includes adaptations of music from the original version. It was the final game released for the Master System in North America. The Master System version was re-released for Wii's Virtual Console service in North America and Europe in August 2008. The Game Gear version was re-released for the Nintendo 3DS Virtual Console on June 13, 2013, and included as an unlockable game in Sonic Adventure DX: Director's Cut for GameCube and Windows and Sonic Mega Collection Plus for PlayStation 2, Xbox, and Windows.

''Sonic the Hedgehog Genesis''

To mark the game's fifteenth anniversary, a port for the Game Boy Advance, Sonic the Hedgehog Genesis, was released on November 14, 2006, in the United States. While the port is mostly identical to the original, it includes several new features not seen in the original Genesis release, such as the ability to save game progress and the inclusion of the Spin Dash move. This version, unlike others, received poor reviews, with a Metacritic score of 33/100. The chief complaints concerned its poor conversion to the Game Boy Advance, resulting in a bad performance and poor implementation of the original music and gameplay.

As a response to the poor reception and claims that the system could not handle the original game, Simon "Stealth" Thomley, who later assisted with the development of the 2013 mobile port, released an unofficial, proof-of-concept version of Sonic the Hedgehog for the system. The unofficial version contains a complete Green Hill Zone and two bonus stages, as well as Tails and Knuckles as playable characters.

2013 remaster

A remastered mobile port was released on iOS on May 15, 2013, with an Android version following the next day. This version was developed by Christian "Taxman" Whitehead and Simon Thomley of Headcannon from scratch using the Retro Engine, previously used in the 2011 remaster of Sonic CD. This port features several enhancements, such as widescreen graphics, the optional ability to Spin Dash, an additional bonus stage, a time attack mode and the unlockable option to play as Tails or Knuckles; it additionally features a heavily expanded debug mode, which allows for use of unused elements and elements from more recent games (such as the characters' super forms). The iOS version was updated in 2016, adding compatibility with Apple TV.

''3D Sonic the Hedgehog''

A Nintendo 3DS version, 3D Sonic the Hedgehog, was released as part of the 3D Classics line in 2013. This version, unlike most downloadable re-releases of the game, is not emulated; rather, the code was restructured to take advantage of the 3DS system's stereoscopic 3D graphics and comes with additional enhancements, such as the option to use the Spin Dash move, a CRT-style filter, and the option to start from any level.

Compilation releases

Main article: List of Sonic the Hedgehog compilations

With its sequels for the Genesis, Sonic the Hedgehog has been ported for a wide range of home and handheld consoles and personal computers through compilations. The first collection it appeared in was Sonic Compilation (1995) for the Genesis. It has since appeared in Sonic Jam (1997) for the Saturn, Sonic Mega Collection (2002) for the GameCube, Sonic Mega Collection Plus (2004) for the PlayStation 2 and Xbox, Sega Genesis Collection for the PlayStation 2 and PSP, Sonic's Ultimate Genesis Collection (2009) for the Xbox 360 and PlayStation 3, Sonic Classic Collection (2010) for the Nintendo DS, Oculus Arcade for the Oculus Rift, and Sega Genesis Classics (2018) for Windows, PlayStation 4, Xbox One and Nintendo Switch. The 2013 remaster was included in the 2022 compilation Sonic Origins. This remaster saw Amy Rose becoming a playable character in an upgraded version of Origins.

Downloadable releases

Sonic the Hedgehog has been available for all three major seventh-generation video game consoles. It was part of the Wii Virtual Console at the service's 2006 introduction, and was released for the Xbox Live Arcade and PlayStation Network shortly afterwards. The game was released for the iPod Classic, iPod video, and video-capable iPod Nano models in 2007 and for Apple's iOS in April 2009. Sonic the Hedgehog became available on GameTap in September 2009. In October 2010, it was released on Windows via Steam. The game was ported to Android and released in December 2012. Additionally, it is an unlockable reward in the console versions of Sonic Generations. The 2013 remaster was made available on the Sega Forever service on iOS and Android in June 2017. A port for the Nintendo Switch was released on September 20, 2018 as part of M2's Sega Ages line of rereleases. It adds features including the ability to use moves from Sonic 2 and Sonic Mania, a challenge mode, a time attack for the first stage, and features from the 3DS rereleases of the game and its sequel.

Canceled versions

U.S. Gold acquired the rights to make a version of Sonic the Hedgehog for the Amiga, ZX Spectrum, Commodore 64, Amstrad CPC and Atari ST personal computers, but these went unreleased. Several screenshots exist, some of which resemble the 8-bit version. An enhanced port for the Sega CD was also planned, but was canceled in favor of Sonic CD.

Reception

5/5 Golden Joystick Awards Going Live Viewers Award

Sales

Sonic the Hedgehog was a commercial success. It became America's best-selling video game for several months in 1991, outselling Super Mario. By Christmas 1991, Sonic the Hedgehog had sold nearly 1 million game cartridges in the United States. It was also Blockbuster Video's highest-renting game of the year. In the United Kingdom, it was the top-selling Mega Drive game for two months following its release.

Sonic the Hedgehog was the best-selling home video game of 1991, with 2 million copies sold worldwide by the end of the year, becoming Sega's best-selling home video game up until then. In 1991, Sonic the Hedgehog helped Sega generate a gross revenue of in console sales and capture a 65% share of the European console market. Sonic the Hedgehog set a Sega software sales record with 2.8 million cartridges sold by March 1992, including 1.8 million copies in the United States and another 1 million in Europe and Japan. The game went on to sell 3.7 million units by October 1992, and 4.5 million copies worldwide by November 1992. By 1997, the game had sold over 14 million copies worldwide, and earned over ( adjusted for inflation), higher than the typically grossed by a blockbuster movie at the time.

The original version bundled with the Sega Genesis/Mega Drive hardware had sold over 15 million copies . The mobile game version also had eight million paid downloads by 2008, 482,960 units were sold on Xbox Live Arcade , and 10 million paid Android downloads were sold as of 2017 bringing total sales to million worldwide across all platforms.

Contemporary reviews

Sonic the Hedgehog was praised by critics, with scores above 90% from most video game magazines at the time. It was considered Sega's answer to Nintendo's widely popular Mario series, as it was a platformer featuring the company's mascot. In a preview following its CES debut in January 1991, John Cook of Computer and Video Games called it the most impressive game at the show and said it was "another jumpy jumpy game in the Mario mould, but with an astonishing turn of speed and great music." Upon release, Paul Rand of Computer and Video Games compared the two in depth and characterized Sonic the Hedgehog as being faster, with brighter colors and Super Mario World as having more "depth of play". Frank Ladoire of ** believed Sonic the Hedgehog was part of a new generation of games that demonstrate that the Mega Drive is capable of "beautiful things" in the technical department.

Reviewers praised the colorful, detailed graphics. Rand called its color scheme "lively, but never garish", praising the interaction of color with detail in the sprites, backgrounds, and animations and describing its graphics as the best available for the Mega Drive. Reviewer Boogie Man of GamePro called the intricate backgrounds "eye-popping" and "gorgeous", which was echoed by Mean Machines. The Lessers (Hartley, Patricia, and Kirk) of Dragon claimed the graphics made Sonic a possible contender for the best game of 1991 and GameZone called the animation "some of the smoothest and fastest ... ever seen". Julian Boardman of Raze praised the "colourful and highly detailed" backdrops and "fabulous" sprites. The music and sound effects were also well received; Dragon called them "great", and GameZone "amazing". Rand praised the "catchy" soundtrack, calling some of the sound effects "absolutely brilliant". Although Mean Machines called the songs "vaguely appealing", the sound effects were better appreciated. However, Boardman of Raze considered the music "a little boring".

Critics cited the fast gameplay, unprecedented in platformers. The difficulty was disputed, described as "impossible" by Rand and "average" by EGM. Rand said about the gameplay in general that it "plays like a dream"; according to GameZone it would enchant players for hours, and Boogie Man praised Sonic Team's ability to provide an engaging experience primarily from running and jumping. Although EGM, Dragon, Paul of Mean Machines and Boardman of Raze praised the level design (especially the hidden rooms), Paul found losing all of one's rings frustrating.

Bob Strauss of Entertainment Weekly gave the game an A+ and wrote that it was a very fast game, yet never felt chaotic or impossible, and they later named it the best game available in 1991.

Awards

At the 1991 Golden Joystick Awards, Sonic the Hedgehog won Overall Game of the Year. In the 1991 Electronic Gaming Monthly awards, Sonic the Hedgehog won Game of the Year. At the European Computer Trade Show (ECTS) awards, it won the awards for Best Video Game and Going Live Viewers Award. In 1992, Mega ranked Sonic as their third-favorite Genesis game. In 1995, Flux rated the game fourth in its "Top 100 Video Games". In 1996, GamesMaster ranked the game 78th on their "Top 100 Games of All Time". In 2016, The Strong National Museum of Play inducted Sonic the Hedgehog to its World Video Game Hall of Fame.

Retrospective reviews

Retrospective reception has been positive, with an 86% rating at the review aggregator GameRankings based on nine reviews published online in the 2000s. Sonic the Hedgehog has maintained its popularity, and has since been considered one of the greatest video games of all time.

Frank Provo of GameSpot described the game as "one of the best platformers of all time", finding that despite technical issues in the Game Boy Advance port "after all these years, the underlying graphics, audio, and gameplay still hold up". Lucas M. Thomas of IGN agreed that it stood the test of time. Writing in The Guardian, Keith Stuart observed that Sonic the Hedgehogs emphasis on speed and pinball mechanics dramatically departs from generally accepted precepts of game design, requiring that players "learn through repetition rather than observation" as "the levels aren't designed to be seen or even understood in one playthrough." However, Stuart concluded that "sometimes in Sonic, when you get better, or through sheer luck, things take off, every jump is right, every loop-the-loop is perfect, and you're in the flow, sailing above the game's strange structure ... Sonic is incorrect game design and yet ... it's a masterpiece."

Legacy

Primarily because of its Genesis bundling, Sonic the Hedgehog was a factor in popularising the console in North America, thus solidifying Sega as a competitor to Nintendo and their Super Nintendo Entertainment System. During October–December 1991, with the game's success, the Genesis outsold the SNES by two to one; at its January 1992 peak it gained a foothold in the industry and had 65 percent of the market for 16-bit consoles. Although Nintendo eventually overtook Sega, it was the first time since December 1985 that Nintendo did not lead the console market.

Sonic the Hedgehog inspired similar platformers starring animal mascots, including Bubsy, Aero the Acro-Bat, James Pond 3, Earthworm Jim, Zero the Kamikaze Squirrel, and Radical Rex. "Animal with attitude" games carried over to the next generation of consoles, with Crash Bandicoots Naughty Dog and Gexs Crystal Dynamics citing Sonic as a major inspiration.

Sonics success led to an extensive media franchise, with the first of many sequels, Sonic the Hedgehog 2, released the following year. It has generated dozens of additional games and a large cast of recurring characters, keeping Sonic and Robotnik (later renamed as Eggman) mainstays, and continued beyond Sega's exit from the console industry after the Dreamcast. The series has ventured from platformers to fighting, racing, role-playing, and sports games, and also expanded into anime, manga, cartoons comic books, novels, and toys. Sonic the Hedgehog is one of the best-selling video game franchises of all time, with over 140 million copies sold or downloaded worldwide across consoles, PC's, mobile phones and tablets by May 2014. The game's first level, Green Hill Zone, has been featured in later games such as Sonic Adventure 2, Sonic Generations, Sonic Mania, Sonic Forces, and the Super Smash Bros. series.

The game inspired a number of unofficial variants, including Somari, a pirated Nintendo Entertainment System conversion featuring Nintendo's Mario character in levels from the original Sonic game, Sonic the Hedgehog Megamix, a total conversion mod of the original game, and Sonic 1 Boomed, a ROM hack which implements Sonic's redesign from the Sonic Boom animated series.

An incomplete prototype build of the game were leaked and released by Hidden Palace on January 1, 2021.

Notes

References

Sources

References

1. (1 July 1991). "Penn to Paper".
2. "Sonic The Hedgehog". [[Killer List of Video Games]].
3. Jack Yarwood. (January 24, 2023). "Sonic Character Designer Shares Images Of The Game That Evolved Into Sonic". Time Extension.
4. Power, Ed. (June 23, 2021). "How Sega conquered the video games industry with Sonic the Hedgehog – and then threw it all away".
5. Thomas, Lucas M.. (January 26, 2007). "Sonic the Hedgehog VC Review".
6. Mariott, Scott Alan. "Sonic the Hedgehog". [[Allgame]].
7. (June 23, 1991). "Sonic the Hedgehog". Sega.
8. (20 January 1994). "Sonic: A brief history".
9. (19 November 1992). "Feature: When did you get yours?".
10. (February 2012). "The Making of Sonic the Hedgehog". [[Imagine Publishing]].
11. (March 21, 2018). "Sonic the Hedgehog's origin story, according to the devs who made him".
12. Horowitz, Ken. (December 5, 2006). "Interview: Mark Cerny". Sega-16.
13. Claiborn, Samuel. (June 26, 2014). "21 Crazy Facts About Sonic and the Console War He Started".
14. Ponce, Tony. (February 27, 2013). "Review: The History of Sonic The Hedgehog".
15. (August–September 1992). "Interview with Yuji Naka: The Creator of ''Sonic The Hedgehog''".
16. Kennedy, Sam. "Sonic Boom".
17. Smith, Sean. (2006). "Company Profile: Sonic Team". Imagine Publishing.
18. (2000-05-24). "セガがソフトウェア研究開発部門を分社化".
19. (October 2000). "Sega's new beginning". [[Future plc]].
20. (2013). "Interview With Naoto Ôshima". UDON Entertainment Corp.
21. Sam Loveridge. (June 23, 2016). "14 things you didn't know about Sonic the Hedgehog".
22. McFerran, Damien. (2023-01-26). "PlayStation 5 lead architect Mark Cerny talks Sega, Michael Jackson and Yuji Naka".
23. (2016). "Retro Gamer Sega Archives". Imagine Publishing.
24. (2014). "Yuji Naka Game Designer". Read-Only Memory.
25. Ken Horowitz. (June 11, 2007). "Developer’s Den: Sega Technical Institute". Sega-16.
26. (2013). "Interview With Yuji Naka". UDON Entertainment Corp.
27. Toyama, Yuichi. (May 15, 2013). "3DソニックDL記念、ソニックの思い出１：'90年3月～4月、某HELP仕事のために広島→羽田に出向した。数週間お邪魔した部署は、期の変わり目だったせいか2研→9研と名前を変えた。近くの席に中さんが居て、MDのソフト開発をしていた…が、MDなのに画面がグルグル回ってて凄かった！".
28. (2013). "The History Of Sonic the Hedgehog". UDON Entertainment Corp.
29. GI Staff. (August 2003). "Sonic's Architect: GI Interviews Hirokazu Yasuhara".
30. [[Yuji Naka]]. (June 23, 2018). "Sonic the Hedgehog in early development; Sega R&D news footage from February 1990". [[YouTube]].
31. (June 24, 2016). "Sonic Team's legendary creators reveal the truth behind the birth, success, and rebirth of "Sonic the Hedgehog" on its 25th anniversary in this permanent edition packed with secret materials! (1/5)". [[Famitsu]].
32. Thomason, Steve. (January 2007). "Birth of a Hedgehog". [[Future Publishing]].
33. (September 2001). "The Making of ... Sonic The Hedgehog". [[Future plc.
34. Kemps, Heidi. (September 30, 2005). "Sega's Yuji Naka Talks!". [[GameSpy]].
35. (November 30, 1990). "SPEC: Volume #7". [[Sega.
36. (January 1997). "ソニックチーム物語". [[SB Creative.
37. Nakamura, Masato. (February 17, 2021). ""Emerald Hill Zone"! {{!}} DREAMS COME TRUE".
38. "中村正人 from DREAMS COME TRUE / ソニック・ザ・ヘッジホッグ1&2 サウンドトラック【CD】". Universal Music Japan.
39. (1994). "Sega Video Game Illustrations". Nippon Shuppan Hanbai (Deutschland) GmbH.
40. (2013). "The History Of Sonic the Hedgehog". UDON Entertainment Corp.
41. (2018-11-08). "Sonic The Hedgehog was originally from Nebraska, ate trash".
42. (2014). "Sega Mega Drive/Genesis Collected Works". Read-Only Memory.
43. "Sonic the Hedgehog – 1991 Developer Interview". Shmuplations.
44. [[Sega]]. link
45. (29 November 1991). "Super NES, Sega Genesis in 16-bit duel". [[Chicago Tribune]].
46. (December 1991). "Games for Grown-Ups: Speedy sprites". Hearst Magazines.
47. Earth Angel. (March 1992). "Sega Master Pro Review: Sonic Boom".
48. (February 2011). "Interview with Yuzo Koshiro". Square Enix Music Online.
49. McFerran, Damien. "Retroinspection: Master System". [[Imagine Publishing]].
50. Thomas, Lucas M.. (August 4, 2008). "Sonic the Hedgehog (Master System Version) Review".
51. "Search Result". [[Pan European Game Information]].
52. Sleeper, Morgan. (June 15, 2013). "Sonic the Hedgehog (3DS eShop / Game Gear)".
53. (June 18, 2003). "[[Sonic Adventure DX: Director's Cut]]". [[Sega]].
54. Metts, Jonathan. (June 23, 2006). "News Article: Sonic on GBA for 15th Anniversary". Nintendo World Report.
55. "Sonic the Hedgehog Genesis for Game Boy Advance Reviews".
56. Provo, Frank. (November 20, 2006). "Sonic the Hedgehog Genesis Review".
57. "Sonic 1 GBA/DS".
58. Mitchell, Richard. (May 16, 2013). "Sonic the Hedgehog speeds to Android today". Joystiq.
59. (May 27, 2013). "A Guide to 'Sonic the Hedgehog' 2.0's Hidden Level-select, Debug Mode, and Many More Secrets".
60. (March 17, 2016). "'Sonic the Hedgehog' Remaster Now on Apple TV, 'Sonic 2' and 'Sonic CD' Later This Month".
61. "3D Sonic the Hedgehog".
62. (February 12, 2014). "3D Sonic the Hedgehog review". Official Nintendo Magazine UK.
63. ''[[Sonic Compilation]]'' instruction manual, p. 3.
64. Nutter, Lee. (August 1997). "Review: Sonic Jam". [[EMAP]].
65. Mirabella, Fran. (November 12, 2002). "Sonic Mega Collection: A stellar compilation with plenty of trimmings.".
66. Goldstein, Hilary. (November 3, 2004). "Sonic Mega Collection Plus: Step into the way-back machine to the days of 16-bit brilliance.".
67. Miller, Greg. (February 12, 2009). "Sonic's Ultimate Genesis Collection Review".
68. Harris, Craig. (March 5, 2010). "Sonic Classic Collection Review".
69. Lang, Ben. (November 10, 2015). "Oculus Arcade Now Available on All Gear VR With 21 Titles".
70. (May 27, 2021). "Sonic Origins Spin Dashes To "The Latest Platforms" Next Year".
71. "Sonic Origins Plus Adds Amy As Playable Character, Game Gear Games, And More This June".
72. "Sonic the Hedgehog Arcade".
73. "Sonic The Hedgehog™". PlayStation.com.
74. Cook, Brad. "Sonic The Hedgehog: Grab the rings". [[Apple Inc..
75. Buchanan, Levi. (May 21, 2009). "Sonic the Hedgehog iPhone Review".
76. "Sonic the Hedgehog – Play Now – GameTap". GameTap.
77. "SEGA Genesis Classics: Series III on PC!". SEGA Blogs.
78. (October 26, 2013). "Sonic the Hedgehog on Steam". [[Valve Corporation.
79. "Sonic The Hedgehog".
80. "Sonic The Hedgehog".
81. Fahey, Mike. (October 26, 2011). "There's a Little Extra Classic Sonic Lurking in Sonic Generations".
82. "Free versions of 'Sonic the Hedgehog' and other classic Sega games are coming to iPhone and Android".
83. (September 13, 2018). "Sega Ages' First Wave Of Games In Sonic the Hedgehog And Thunder Force IV Arrives September 20".
84. Romano, Sal. (August 27, 2018). "Sega Ages: Sonic the Hedgehog and Thunder Force IV delayed to September".
85. (July 19, 2018). "Sonic The Hedgehog Coming to Switch Next Month - With New Features".
86. "Unreleased Sonic the Hedgehog Games".
87. (September 1, 1991). "Magicamigamente Sonic!".
88. (August 1992). "Coming Attractions". MegaPlay.
89. Whitta, Gary. (August 1991). "Sonic the Hedgehog".
90. (8 October 1991). "Sonic the Hedgehog".
91. (1991-07-08). "ソニック・ザ・ヘッジホッグ".
92. (August 1991). "Sonic The Hedgehog".
93. (October 1991). "The Role of Computers".
94. (July 1991). "Genesis – Sega / Sonic the Hedgehog".
95. Boogie Man. (June 1991). "Genesis Pro Review: Hedgehog Heaven".
96. Ladoire, Frank. (July 1991). "''Sonic The Hedgehog''".
97. (October 1991). "Sonic".
98. (July–August 1991). "Sonic the Hedgehog".
99. (July–August 1991). "Sonic".
100. Boardman, Julian. (September 1991). "''Sonic the Hedgehog''". [[Newsfield]].
101. Strauss, Bob. (August 23, 1991). "Sonic The Hedgehog". [[Meredith Corporation]].
102. (July 1991). "Mega Drive Review: Sonic the Hedgehog".
103. (September 1991). "''Sonic the Hedgehog''". [[Future plc]].
104. (December 2, 1992). "Sega reports strong 'Sonic 2' sales". [[United Press International.
105. (January 1992). "Pro News Report". [[International Data Group]].
106. (15 July 1991). "CVG Charts".
107. (15 August 1991). "CVG Charts".
108. (November 24, 1992). "Sonic the Hedgehog 2 Launch (Sonic 2sday)". [[Sega of America]].
109. (13 September 2001). "Super Sonic". [[Los Angeles Times]].
110. (5 January 1992). "Making a Difference; The Hedgehog Takes Hold". [[The New York Times]].
111. (20 December 1992). "A MegaTech Christmas Carol".
112. (1993). "Tokyo Business Today". [[Toyo Keizai]].
113. (1992). "Asiaweek". Asiaweek Limited.
114. (October 1992). "Sonic the Hedgehog 2: Review".
115. (11 June 1997). "A blast from the past!".
116. (16 July 1997). "Review: Sonic Jam".
117. (1997). "Opening the Doors to Hollywood: How to Sell Your Idea, Story, Book, Screenplay, Manuscript". [[Three Rivers Press]].
118. (February 16, 2009). "Sonic the Hedgehog GameTap Retrospective Pt. 3/4". [[GameTap]] (user gametap).
119. "Sonic the Hedgehog GameTap Retrospective (Alternative Compilation Upload)".
120. Parfitt, Ben. (May 29, 2008). "Sonic rings mobile success".
121. (January 20, 2012). "Xbox Live Arcade by the numbers - the 2011 year in review". [[Gamasutra]].
122. Tavares, Pedro. (2018-01-23). "Sonic apps in the Google Play published by SEGA leak users' data".
123. (16 February 1991). "CVG News: Special Report".
124. (November 1991). "Mega Drive: ''Sonic the Hedgehog''".
125. Strauss, Bob. (November 22, 1991). "Video Games Guide".
126. (May 1992). "News: Luvvies! Dahlings!". [[EMAP]].
127. ''Electronic Gaming Monthly's 1992 Video Game Buyer's Guide'', pages 60–61
128. (11 June 1992). "News". [[Zero (video game magazine).
129. (October 1992). "Sonic the Hedgehog".
130. (April 1995). "Top 100 Video Games". Harris Publications.
131. (July 1996). "Top 100 Games of All Time". GamesMaster.
132. "Sonic the Hedgehog". [[The Strong]].
133. "Sonic the Hedgehog for Genesis". [[CBS Interactive]].
134. "Sonic the Hedgehog: Genesis".
135. "Sonic the Hedgehog for iOS (iPhone/iPad)". CBS Interactive.
136. "3D Sonic the Hedgehog for 3DS Reviews". CBS Interactive.
137. "Sonic the Hedgehog (Live Arcade) for Xbox 360 Reviews". CBS Interactive.
138. Reed, Kristan. (July 16, 2007). "Sonic the Hedgehog Review".
139. Kasavin, Greg. (November 19, 2006). "''Sonic the Hedgehog'' Review".
140. Thomas, Lucas M.. (January 26, 2007). "Sonic the Hedgehog VC Review".
141. (20 November 2006). "Review: Sonic the Hedgehog (Virtual Console / Sega Mega Drive)".
142. (January 2005). "The 10 Most Important Games".
143. Stuart, Keith. (July 27, 2017). "Why Sonic the Hedgehog is 'incorrect' game design". [[The Guardian]].
144. (January 2002). "This Month in Gaming History".
145. Cifaldi, Frank. "Gamasutra – The Art & Business of Making Games".
146. Edge staff. (August 25, 2010). "Making Of: James Pond II – Robocod". [[Future plc.
147. Kalata, Kurt. (October 10, 2008). "Earthworm Jim". Hardcore Gaming 101.
148. (September 6, 2013). "10 Worst Video Game Mascots".
149. (August 2016). "Games No One Remembers: RADICAL REX".
150. (October 1998). "From Rags to Riches: ''Way of the Warrior'' to ''Crash 3''". [[FuncoLand.
151. (February 2, 2011). "Making Crash Bandicoot – part 1". All Things Andy Gavin.
152. Buchanan, Levi. (December 2, 2008). "What Hath Sonic Wrought?, Vol. 4".
153. Buchanan, Levi. (February 20, 2009). "Where Did Sonic Go Wrong?".
154. Harris, Craig. (January 13, 2004). "Sonic Battle".
155. MacDonald, Ryan. (December 22, 1997). "Sonic R Review".
156. Bozon, Mark. (September 24, 2008). "Sonic Chronicles: The Dark Brotherhood Review".
157. Thompson, Scott. (November 8, 2013). "Mario & Sonic at the Sochi 2014 Olympic Winter Games Review".
158. GamesRadar_US. (April 23, 2008). "The absolute worst Sonic moments". [[GamesRadar]].
159. (1992). "[[Sonic the Hedgehog (manga)". [[Shogakukan]].
160. Yehl, Joshua. (July 16, 2014). "Archie to Publish Sonic Boom Comic Book Series".
161. Fullerton, Charlotte. (March 1, 2007). "Desperately Seeking Sonic". Grosset & Dunlap.
162. (December 2, 2004). "McDonald's and SEGA Reveal Details of New Happy Meal Promotion Featuring Sonic and 'Search for the Silver Game'". GameZone.
163. Aamoth, Doug. (November 15, 2012). "All-TIME 100 Video Games".
164. Parker, Kellie. (May 29, 2014). "Introducing Sticks to the Sonic Boom Franchise". Sega Blog.
165. Parker, Kellie. (October 26, 2011). "Play Sonic 1 in X360 & PS3 Versions of Sonic Generations". [[Sega]] Blog.
166. Goldfarb, Andrew. (July 23, 2016). "Comic-Con 2016: Sonic Mania Announced".
167. "Green Hill Zone".
168. Totilo, Stephen. (March 28, 2007). "Mario, Sonic Facing Off For Game Of Olympic Proportions". [[MTV News]].
169. (January 3, 2007). "Sonic Megamix: Welcome Back to 1991".
170. McWhertor, Michael. (April 7, 2016). "ROM hack brings Sonic Boom's Annoying Qualities To The Original Sonic the Hedgehog".
171. Alexander, Cristina. (2021-01-03). "Here's A Look At The Official Prototype For Sonic The Hedgehog (1991)".