Sonic the Hedgehog (1991 video game)
Sonic the Hedgehog[a] is a platform game developed by Sonic Team and published by Sega for the Sega Genesis home video game console. It was released in North America in June 1991 and in PAL regions and Japan the following month. The game features an anthropomorphic hedgehog named Sonic in a quest to defeat Dr. Robotnik, a scientist who has imprisoned animals in robots and stolen the powerful Chaos Emeralds. The gameplay involves collecting rings as a form of health, and a simple control scheme, with jumping and attacking controlled by a single button.
Development began in 1990 when Sega ordered its developers to create a game featuring a mascot for the company. After considering a number of suggestions, the developers decided on a blue hedgehog and named themselves "Sonic Team" to match their character. Sonic the Hedgehog, designed for fast gameplay, was influenced by games by Super Mario series creator Shigeru Miyamoto. Sonic the Hedgehog uses a novel technique that allows Sonic's sprite to roll along curved scenery, which originated in a tech demo created by programmer Yuji Naka.
Sonic the Hedgehog was well received by critics, who praised its visuals, audio, and gameplay. It was also commercially successful, establishing the Genesis as a key player in the 16-bit era and allowing it to compete with Nintendo and their Super Nintendo Entertainment System console. The game has been ported a number of times, and inspired several clones, a successful franchise, and adaptations into other media. It is often cited as one of the greatest video games of all time.
Sonic the Hedgehog is a 2D side-scrolling–platform video game. The gameplay centers around Sonic's ability to run at high speed through levels that include springs, slopes, bottomless pits, and vertical loops. The levels are populated with hazards in the form of robots inside which Dr. Robotnik has trapped animals. Destroying a robot frees the creature, but is not necessary to complete the game. The player must also avoid touching spikes, falling into bottomless pits, and being crushed by moving walls or platforms, as well as drowning, which may be prevented by breathing air bubbles from vents. Sonic's main means of attack is the Spin Attack, in which he curls into a ball and rapidly spins his body, damaging enemies and certain obstacles upon collision. This may be performed by jumping or by rolling on the ground.
At the start of the game, the player is given three lives, each of which may be lost if Sonic collides with hazardous enemies or objects while in possession of no rings, falls to the bottom of the level screen, or exceeds an act's ten-minute time limit. Signposts act as checkpoints to allow Sonic to return to the most recently activated post when he loses a life. The time resets when he returns to the checkpoint. The game ends when the player runs out of lives, although the player may return to the beginning of the act with three lives if the player has any continues.
Scattered around each level are gold rings. Collecting 100 rings rewards the player with an extra life. Rings act as a layer of protection against hazards: if Sonic holds at least one ring when he collides with an enemy or dangerous obstacle, all his rings will scatter. He can recollect some of them again before they disappear. If he is hit without holding any rings, he loses a life. Shields and temporary invincibility can be collected to provide additional layers of protection, but certain hazards, such as drowning, being crushed, bottomless pits, or running out of time, kill Sonic regardless of rings or other protection.
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. Robotnik for a boss fight. For most of the fights, Robotnik's vehicle is fitted with different weapons. After completing the sixth zone, the player continues directly to the single-level "Final Zone" for a last encounter with Robotnik inside a large machine environment. Destroying Robotnik's machine ends the game. A brief animation shows Sonic's return to the first zone, with animals liberated from Dr. Robotnik.
Optionally, if Sonic reaches the end of any zone's Act 1 or Act 2 while holding at least 50 rings, a large ring appears through which he can jump to enter a "special stage". In the Special Stages, 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.
In an attempt to steal the six Chaos Emeralds and harness their power, the evil Dr. Ivo Robotnik[b] has trapped the animal inhabitants of South Island in aggressive robots and stationary metal capsules. The player controls Sonic, who aims to halt Robotnik's plans by freeing his animal friends and collecting the emeralds himself. If the player collects all the Chaos Emeralds and completes the game, an ending sequence is shown. If all the emeralds are not collected, Robotnik taunts the player while juggling any of the Chaos Emeralds not collected by the player.
Background and character design
In 1990, Sega ordered its in-house development studio to develop a game featuring a mascot for the company. Sega president Hayao Nakayama wanted a character as iconic as Mickey Mouse. Sega had competition with Nintendo, who was dominant at the time (particularly after the release of the successful Super Mario Bros. 3), and Sega wanted a foothold in the industry. Although the company had some limited success with Genesis ports of its arcade games, it knew this would not be enough.
The team developed ideas for characters, an engine, and gameplay mechanics. Development emphasized speed, so Sega eliminated character designs not associated with fast animals, as well as fast creatures like kangaroos and squirrels. One idea, a rabbit able to grasp objects with prehensile ears, showed promise at first but was too complex for the available hardware. The team narrowed its search to animals that can roll into a ball, their idea for an attacking move. Designers then realized that this would not seem aggressive enough, so they focused on two animals with spikes: armadillos and hedgehogs. The hedgehog character, first proposed by Naoto Ohshima, prevailed, although the armadillo would later become the basis for Mighty the Armadillo, who later appeared in 1993's SegaSonic the Hedgehog. Ohshima has since admitted that he created Sonic's basic design by combining Felix the Cat's head with Mickey Mouse's body. Ohshima explained that his inspiration for creating Sonic was Sega wanting a game that would be successful in the United States and a new mascot concurrently. He was working with Naka with a prototype game, and Ohshima was thinking of design ideas with the toy and stationery department. Before Sonic was chosen, other characters, including a rabbit and a bearded man who would ultimately become Dr. Robotnik, were created. One summer, 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. Ohshima explained that this was because he wanted support for his ideas.
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. 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 look 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. Needlemouse", but the eight-member team changed his name to "Sonic" and took the name Sonic Team.[c] Ohshima stated 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, but 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 and initially proposed a full-scale recreation of the character, but compromised with Sonic Team to simply make design changes. The antagonist ended up being 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 completed, Sega turned to programmer Yuji Naka, who had impressed them through his work on Phantasy Star and the Genesis port of Ghouls 'n Ghosts. Naka was a fan of Super Mario Bros. but desired something faster, so the game was made to play quickly, which was where he focused most of his effort. Naka explained that the reason he wanted a fast game is because he 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: two programmers, two sound engineers, and three designers, although it began with just Naka and Ohshima. People came onto the team as the need for content increased. After being assigned a project with the code name "Defeat Mario", Naka and Ohshima began work, but encountered problems: Ohshima's Rabbit proved hard to program. Catching items and throwing them caused the action's rhythm to break. Naka stated that the rabbit was not suitable for his game engine, and he also wanted the game to be playable with only one button. Hirokazu Yasuhara came onto the team to supervise Naka and Ohshima and develop levels. He became the lead designer due to his greater experience, and found the way to make the game playable with only one button by having Sonic do damage by jumping. The trio came up with the idea of him rolling into a ball. After the hedgehog character was chosen, many characters were redrawn, and the team agreed on the environments visual complexity, with particular focus on the colors. After this, four people came onto the team to speed development up.
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 the problem by developing an algorithm that enabled the animation to retain fluidity. Sonic was able to cross levels quickly without the animation slowing down, and all that was left was the optimization of the game's 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 gameplay originated with 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. 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 the 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 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.
Naka, Ohshima, 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 special 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 "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. He stated that he found the process "very interesting". 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. The zones were based on designs by Naka and Ohshima, with the goal of creating the world's fastest action game. According to Ohshima, Robotnik was based on Humpty Dumpty.
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.
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 when asked to create the soundtrack, as he had just started with Dreams Come True, but accepted as he was inspired by the team's desire to outperform Nintendo. Nakamura said the hardest part of creating the soundtrack was the 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.
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". The game was not revealed until the January 1991 International Consumer Electronics Show because Sega wanted to wait until the right time and because they saw an opportunity to "steal the show". At the show, Sonic the Hedgehog was believed to be the most impressive game shown, 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, became involved, and playtested the game 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 Consumer Electronics Show. It was released in North America on June 23, 1991, and in the PAL regions and Japan the following month. Sega of America packaged it with American Genesis consoles, replacing Altered Beast. This tactic 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 large-scale marketing campaign, promoting Sonic as its mascot.
Other versions and rereleases
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 special 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. 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 special stages, as well as Tails and Knuckles as playable characters.
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 special 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.
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 Sega Saturn, Sonic Mega Collection (2002) for the Nintendo 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 Microsoft Windows, PlayStation 4, Xbox One and Nintendo Switch.
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. It was also made available on the Sega Forever service on iOS and Android in June 2017. A port for Nintendo Switch was released on September 20, 2018 as part of the 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.
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 scrapped in favor of Sonic CD.
Sonic the Hedgehog was praised by critics, with an 86% rating at the review aggregator GameRankings. It was considered Sega's answer to Nintendo's widely popular Mario series, as it was a platformer featuring the company's mascot. 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 Génération 4 believed Sonic the Hedgehog was part of a new generation of games that demonstrate that the Genesis 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 Genesis. 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.
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 Hedgehog's 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." Mega ranked Sonic as its third-favorite Genesis game, and in 2001 Game Informer called it the 24th-greatest game of all time. Sonic the Hedgehog has been a commercial success; the original Genesis version bundled with the Sega Genesis / Mega Drive hardware had sold over 15 million copies by February 2009, and the mobile version had eight million paid downloads by 2008. 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.
Primarily because of its Genesis bundling, Sonic the Hedgehog contributed to the console's popularity in North America. During October–December 1991, the Genesis outsold the Super NES by two to one; at its January 1992 peak it 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 the developers of Crash Bandicoot and Gex citing Sonic as a major inspiration.
Sonic's 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 seen in later other 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.
- Japanese: ソニック・ザ・ヘッジホッグ Hepburn: Sonikku za Hejjihoggu
- Known as Dr. Eggman in the Japanese version
- According to Yuji Naka, Sonic Team was an unofficial name for the studio within Sega that was used during the development of the game; it became their official title when Nights into Dreams was released in 1996.
- "Sonic The Hedgehog". The International Arcade Museum. Killer List of Video Games. Retrieved April 23, 2020.
- Thomas, Lucas M. (January 26, 2007). "Sonic the Hedgehog VC Review". IGN. Retrieved February 23, 2014.
- Mariott, Scott Alan. "Sonic the Hedgehog". Allgame. Retrieved February 6, 2014.
- "Sonic The Hedgehog". Review. Computer and Video Games. No. 117. August 1991. pp. 16–19. ISSN 0261-3697.
- Official player's guide, p. 12.
- Certain Victory Guide Book, p. 8.
- Sonic Team (June 23, 1991). Sonic the Hedgehog. Sega.
- Sega (1991). Sonic the Hedgehog Mega Drive Manual (PAL ed.). p. 30.
- Certain Victory Guide Book, pp. 3,4.
- Official player's guide, pp. 20,28,36,44,52.
- Official player's guide, p. 61.
- "The Making of Sonic the Hedgehog". Retro Gamer. No. 100. Bournemouth: Imagine Publishing. February 2012. pp. 46–49. ISSN 1742-3155.
- Kennedy, Sam. "Sonic Boom". 1UP.com. Archived from the original on June 4, 2011. Retrieved September 24, 2014.
- Claiborn, Samuel (June 26, 2014). "21 Crazy Facts About Sonic and the Console War He Started". IGN. Retrieved February 13, 2014.
- Horowitz, Ken (December 5, 2006). "Interview: Mark Cerny". Sega-16. Retrieved October 12, 2014.
Mark Cerny: Sonic had been a lighter blue, but he was very hard to see against the ocean backgrounds, so his color was darkened at the last moment.
- Ponce, Tony (February 27, 2013). "Review: The History of Sonic The Hedgehog". Destructoid. Retrieved October 11, 2014.
- "Interview with Yuji Naka: The Creator of Sonic The Hedgehog". Sega Visions. Vol. 3 no. 9. August–September 1992. p. 20.
- "Sega's new beginning". Edge. No. 89. Future plc. October 2000. pp. 68–78.
- Naoto Ohshima (2013). Les Editions Pix'n Love (ed.). "Interview With Naoto Ôshima". The History Of Sonic The Hedgehog (Interview). UDON Entertainment Corp. pp. 96–101. ISBN 978-1-926778-96-9.
- Sam Loveridge (June 23, 2016). "14 things you didn't know about Sonic the Hedgehog". DigitalSpy. Retrieved June 10, 2017.
- "Sonic Boom: The Success Story Of Sonic The Hedgehog". Retro Gamer Sega Archives. Bournemouth: Imagine Publishing. 2016. pp. 50–59. ISBN 978-1-78546-372-3.
- Yuji Naka (2014). "Yuji Naka Game Designer". Sega Mega Drive/Genesis Collected Works (Interview). Read-Only Memory. pp. 278, 279. ISBN 978-0-9575768-1-0.
- Yuji Naka (2013). Les Editions Pix'n Love (ed.). "Interview With Yuji Naka". The History Of Sonic The Hedgehog (Interview). UDON Entertainment Corp. pp. 90–95. ISBN 978-1-926778-96-9.
- Les Editions Pix'n Love, ed. (2013). "Zone 1 Genesis". The History Of Sonic the Hedgehog. Ontario: UDON Entertainment Corp. pp. 20–33. ISBN 978-1-926778-96-9.
- GI Staff (August 2003). "Sonic's Architect: GI Interviews Hirokazu Yasuhara". Game Informer. Vol. 13 no. 124. pp. 114–116.
- Thomason, Steve (January 2007). "Birth of a Hedgehog". Nintendo Power. Vol. 20 no. 211. Future Publishing. p. 72.
- "The Making of ... Sonic The Hedgehog". Edge. No. 101. Bath: Future Publishing. September 2001. pp. 118–121. ISSN 1350-1593.
Sonic was delivering [the kind of] high speed no other [game] was capable of, and the Mega Drive allowed this stunning demonstration of rotation during the bonus stages. This was said to be impossible on the hardware at the time.
- Kemps, Heidi (September 30, 2005). "Sega's Yuji Naka Talks!". GameSpy. Retrieved September 23, 2004.
- Naoto Ohshima (2014). "Naoto Ohshima Visual Designer". Sega Mega Drive/Genesis Collected Works (Interview). Read-Only Memory. pp. 328, 329. ISBN 978-0-9575768-1-0.
- "ソニックチーム物語". Sega Magazine (in Japanese). No. 3. SoftBank Creative. January 1997. pp. 9–13. (Translation by Shmuplations. Archived December 17, 2019, at the Wayback Machine).
- "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】" (in Japanese). Universal Music Japan. Retrieved February 20, 2015.
- Sega Video Game Illustrations. Nippon Shuppan Hanbai (Deutschland) GmbH. 1994. ISBN 3-910052-50-9.
- Les Editions Pix'n Love, ed. (2013). "Zone 2 A New Face In The Magazines". The History Of Sonic the Hedgehog. Ontario: UDON Entertainment Corp. pp. 34–41. ISBN 978-1-926778-96-9.
- Keith Stuart (2014). "The Blue Blur". In Wall, Darren (ed.). Sega Mega Drive/Genesis Collected Works. Read-Only Memory. pp. 20–24. ISBN 978-0-9575768-1-0.
- Leadbetter, Rich; Paul, Glancey (July 1991). "Mega Drive Review: Sonic the Hedgehog". Mean Machines. No. 10. pp. 42–44. ISSN 0960-4952. Archived from the original on March 5, 2016. Retrieved February 9, 2012.
- [セガハード大百科] メガドライブ対応ソフトウェア（セガ発売） (in Japanese). Sega. Archived from the original on November 24, 2012. Retrieved December 18, 2015.
- Magazines, Hearst (December 1991). Popular Mechanics. Hearst Magazines. Retrieved January 3, 2017.
- Earth Angel (March 1992). "Sega Master Pro Review: Sonic Boom". GamePro. pp. 57–58.
- Thomas, Lucas M. (August 4, 2008). "Sonic the Hedgehog (Master System Version) Review". IGN. Retrieved September 21, 2014.
- Greening, Chris; Kotowski, Don (February 2011). "Interview with Yuzo Koshiro". Square Enix Music Online. Archived from the original on July 8, 2012. Retrieved September 12, 2014.
- McFerran, Damien. "Retroinspection: Master System". Retro Gamer. No. 44. London, UK: Imagine Publishing. pp. 48–53. ISSN 1742-3155.
- "Search Result". Pan European Game Information. Archived from the original on September 24, 2014. Retrieved September 21, 2014.
- Sleeper, Morgan (June 15, 2013). "Sonic the Hedgehog (3DS eShop / Game Gear)". NintendoLife. Retrieved December 26, 2014.
- Sonic Team (June 18, 2003). Sonic Adventure DX: Director's Cut. Sega.
Description: (SONIC THE HEDGEHOG) This is Sonic's first action game on GAME GEAR. Stop Dr. Eggman from getting his hands on the Chaos Emeralds! One Chaos Emerald is hidden in each zone. Collect them all to view the true ending.
- Goldstein, Hilary (November 3, 2004). "Sonic Mega Collection Plus: Step into the way-back machine to the days of 16-bit brilliance". IGN. Retrieved September 21, 2014.
- Metts, Jonathan (June 23, 2006). "News Article: Sonic on GBA for 15th Anniversary". Nintendo World Report. Retrieved September 12, 2014.
- "Sonic the Hedgehog Genesis for Game Boy Advance Reviews". Metacritic. Retrieved September 12, 2014.
- Provo, Frank (November 20, 2006). "Sonic the Hedgehog Genesis Review". GameSpot. Retrieved October 11, 2014.
- Thomley, Simon. "Sonic 1 GBA/DS". stealth.hapisan.com. Retrieved December 4, 2016.
- Mitchell, Richard (May 16, 2013). "Sonic the Hedgehog speeds to Android today". Joystiq. Retrieved January 11, 2015.
- Nelson, Jared. "A Guide to 'Sonic the Hedgehog' 2.0's Hidden Level-select, Debug Mode, and Many More Secrets". TouchArcade. Retrieved March 31, 2017.
- Dotson, Carter. "'Sonic the Hedgehog' Remaster Now on Apple TV, 'Sonic 2' and 'Sonic CD' Later This Month". TouchArcade. Retrieved March 31, 2017.
- "3D Sonic the Hedgehog". NintendoLife. Retrieved October 12, 2014.
- "3D Sonic the Hedgehog review". Official Nintendo Magazine UK: 87. February 12, 2014.
- Harris, Craig (March 5, 2010). "Sonic Classic Collection Review". IGN. Retrieved September 23, 2014.
- Sonic Compilation instruction manual, p. 3.
- Nutter, Lee (August 1997). "Review: Sonic Jam". Sega Saturn Magazine. EMAP. pp. 68–69.
- Mirabella, Fran (November 12, 2002). "Sonic Mega Collection: A stellar compilation with plenty of trimmings". IGN. Retrieved September 21, 2014.
- Miller, Greg (February 12, 2009). "Sonic's Ultimate Genesis Collection Review". IGN. Retrieved September 23, 2014.
- Lang, Ben (November 10, 2015). "Oculus Arcade Now Available on All Gear VR With 21 Titles".
- "Sonic the Hedgehog Arcade". IGN. Retrieved October 13, 2014.
- "Sonic The Hedgehog™". PlayStation.com. Retrieved October 13, 2014.
- Cook, Brad. "Sonic The Hedgehog: Grab the rings". Apple.com. Archived from the original on July 25, 2008. Retrieved October 11, 2014.
- Buchanan, Levi. "Sonic the Hedgehog iPhone Review". IGN. Retrieved October 13, 2014.
- "Sonic the Hedgehog – Play Now – GameTap". GameTap. Archived from the original on September 17, 2009. Retrieved October 21, 2009.
- "SEGA Genesis Classics: Series III on PC!". SEGA Blogs. Retrieved October 6, 2010.
- "Sonic the Hedgehog on Steam". Valve. October 26, 2013. Retrieved October 13, 2014.
- "Sonic The Hedgehog". Google. Archived from the original on August 21, 2013. Retrieved October 13, 2014.
- "Sonic The Hedgehog". Amazon.com. Retrieved October 13, 2014.
- Fahey, Mike (October 26, 2011). "There's a Little Extra Classic Sonic Lurking in Sonic Generations". Kotaku. Retrieved January 11, 2015.
- Vega, Nick. "Free versions of 'Sonic the Hedgehog' and other classic Sega games are coming to iPhone and Android". Business Insider. Retrieved June 21, 2017.
- Sato (September 13, 2018). "Sega Ages' First Wave Of Games In Sonic the Hedgehog And Thunder Force IV Arrives September 20". Siliconera. Retrieved September 13, 2018.
- Romano, Sal (August 27, 2018). "Sega Ages: Sonic the Hedgehog and Thunder Force IV delayed to September". Gematsu. Retrieved August 27, 2018.
- Raymond, Nicholas (July 19, 2018). "Sonic The Hedgehog Coming to Switch Next Month - With New Features". Screen Rant. Retrieved August 26, 2018.
- "Unreleased Sonic the Hedgehog Games". UGO. Archived from the original on January 5, 2013. Retrieved June 16, 2017.
- Pasquali, Gabriele (September 1, 1991). "Magicamigamente Sonic!". The Games Machine. No. 34. p. 87.
- "Coming Attractions". MegaPlay. 3 (11): 30. August 1992.
- "Sonic the Hedgehog for Genesis". GameRankings. CBS Interactive. Retrieved February 6, 2014.
- "Sonic the Hedgehog for iOS (iPhone/iPad)". GameRankings. CBS Interactive. Retrieved March 31, 2017.
- "Sonic the Hedgehog (Live Arcade) for Xbox 360 Reviews". Metacritic. CBS Interactive. Retrieved September 5, 2018.
- "3D Sonic the Hedgehog for 3DS Reviews". Metacritic. CBS Interactive. Retrieved September 5, 2018.
- Lesser, Hartley; Lesser, Patricia & Lesser, Kirk (October 1991). "The Role of Computers". Dragon. No. 174. pp. 57–64. ISSN 1062-2101.
- "Genesis – Sega / Sonic the Hedgehog". Electronic Gaming Monthly. No. 24. July 1991. p. 24. ISSN 1058-918X.
- Reed, Kristan (July 16, 2007). "Sonic the Hedgehog Review". Eurogamer. Retrieved February 9, 2012.
- Boogie Man (June 1991). "Genesis Pro Review: Hedgehog Heaven" (PDF). GamePro. pp. 42, 43. ISSN 1042-8658. Retrieved March 7, 2017.
- Kasavin, Greg (November 19, 2006). "Sonic the Hedgehog Review". GameSpot. Retrieved September 10, 2014.
- Thomas, Lucas M. (January 26, 2007). "Sonic the Hedgehog VC Review". IGN. Archived from the original on February 17, 2012. Retrieved February 6, 2014.
- Gary Whitta (August 1991). "Sonic the Hedgehog". ACE. No. 47. pp. 54–56.
- Strauss, Bob (August 23, 1991). "'Sonic The Hedgehog". Entertainment Weekly. No. 80. Meredith Corporation. Retrieved December 15, 2018.
- Frank Ladoire (July 1991). "Sonic The Hedgehog". Génération 4 (in French). No. 35. pp. 118–121. ISSN 1624-1088.
- Julian Boardman (September 1991). "Sonic the Hedgehog". Raze. Newsfield (11): 50–52.
- "Sonic the Hedgehog" (PDF). Sega Power. Future plc. September 1991. pp. 9–11.
- "News: Luvvies! Dahlings!". The One. No. 44. EMAP. May 1992. p. 17.
- Electronic Gaming Monthly's 1992 Video Game Buyer's Guide, pages 60–61
- "Mega Drive: Sonic the Hedgehog". GameZone. No. 1. November 1991. p. 97.
- Stuart, Keith (July 27, 2017). "Why Sonic the Hedgehog is 'incorrect' game design". The Guardian. Retrieved July 28, 2017.
- "Sonic the Hedgehog". Mega. No. 1. October 1992. p. 76.
- Cork, Jeff (November 16, 2009). "Game Informer's Top 100 Games Of All Time (Circa Issue 100)". Game Informer. Retrieved December 10, 2013.
- Sonic the Hedgehog GameTap Retrospective Pt. 3/4 (YouTube). GameTap (user gametap). February 16, 2009. Retrieved February 6, 2014.
- Sonic the Hedgehog GameTap Retrospective (Alternative Compilation Upload). Event occurs at 12:40.
- Parfitt, Ben (May 29, 2008). "Sonic rings mobile success". MCV. Retrieved May 29, 2008.
- Bob Strauss (November 22, 1991). "Video Games Guide". Entertainment Weekly. Retrieved January 23, 2019.
- "This Month in Gaming History". Game Informer. Vol. 12 no. 105. January 2002. p. 117.
- Cifaldi, Frank. "Gamasutra – The Art & Business of Making Games". Gamasutra.
- Edge staff (August 25, 2010). "Making Of: James Pond II – Robocod". Edge. Future Publishing. p. 2. Archived from the original on July 21, 2014. Retrieved January 24, 2019.
Unfortunately, I pretty much forgot all that when working on James Pond 3, and I spent too much of the development time chasing after what Sonic had just achieved.
- Kalata, Kurt (October 10, 2008). "Earthworm Jim". Hardcore Gaming 101. Retrieved October 11, 2014.
- Ledford, Jon (September 6, 2013). "10 Worst Video Game Mascots". Arcade Sushi.
- Joest, Mick. "Games No One Remembers: RADICAL REX". GameTyrant.
- "From Rags to Riches: Way of the Warrior to Crash 3". Game Informer. No. 66. United States: Funco. October 1998. pp. 18–19.
- "Making Crash Bandicoot – part 1". All Things Andy Gavin.
- Buchanan, Levi (December 2, 2008). "What Hath Sonic Wrought?, Vol. 4". IGN.
- Buchanan, Levi (February 20, 2009). "Where Did Sonic Go Wrong?". IGN. Retrieved October 11, 2014.
- Harris, Craig (January 13, 2004). "Sonic Battle". IGN. Retrieved October 13, 2014.
- MacDonald, Ryan (December 22, 1997). "Sonic R Review". GameSpot. Retrieved October 13, 2014.
- Bozon, Mark (September 24, 2008). "Sonic Chronicles: The Dark Brotherhood Review". IGN. Retrieved October 13, 2014.
- Thompson, Scott (November 8, 2013). "Mario & Sonic at the Sochi 2014 Olympic Winter Games Review". IGN. Retrieved October 13, 2014.
- GamesRadar_US (April 23, 2008). "The absolute worst Sonic moments". GamesRadar. Retrieved October 13, 2014.
- Kenji Terada (w). "エイミー姫をすくえ!" Sonic the Hedgehog (1992), Shogakukan
- Yehl, Joshua (July 16, 2014). "Archie to Publish Sonic Boom Comic Book Series". IGN. Retrieved October 13, 2014.
- Fullerton, Charlotte (March 1, 2007). Desperately Seeking Sonic. Grosset & Dunlap. ISBN 978-0-448-44479-6.
- "McDonald's and SEGA Reveal Details of New Happy Meal Promotion Featuring Sonic and 'Search for the Silver Game'". GameZone. December 2, 2004. Archived from the original on August 7, 2011. Retrieved July 23, 2014.
- Aamoth, Doug (November 15, 2012). "All-TIME 100 Video Games". Time. Archived from the original on May 6, 2016. Retrieved September 2, 2014.
- Parker, Kellie (May 29, 2014). "Introducing Sticks to the Sonic Boom Franchise". Sega Blog. Archived from the original on March 4, 2016. Retrieved December 25, 2018.
- Parker, Kellie (October 26, 2011). "Play Sonic 1 in X360 & PS3 Versions of Sonic Generations". Sega Blog. Retrieved October 11, 2014.
- Goldfarb, By Andrew. "Comic-Con 2016: Sonic Mania Announced". IGN. Retrieved July 24, 2016.
- "Green Hill Zone". smashbros.com. Retrieved January 20, 2020.
- Totilo, Stephen. Mario, Sonic Facing Off For Game Of Olympic Proportions. MTV News. March 28, 2007.
- Cavalli, Earnest. "Sonic Megamix: Welcome Back to 1991". Destructoid. Retrieved January 3, 2017.
- McWhertor, Michael. "ROM hack brings Sonic Boom's Annoying Qualities To The Original Sonic the Hedgehog". Polygon. Retrieved January 3, 2017.
- Faitingusutajio (1993). ソニックザヘッジホッグ1 & 2必勝攻略法 Sonikku za hejjihoggu ichi to ni hisshō kōryakuhō [Sonic the Hedgehog 1 & 2 Certain Victory Strategy Guide] (in Japanese). ISBN 978-4-575-28232-0.
- Sonic the Hedgehog 1 & 2 : Sega's Official Player's Guide. Hayward, CA: Sega. 1993. ISBN 1-55958-335-5.