Sonic CD
Sonic the Hedgehog CD[lower-alpha 1] is a 1993 platform game for the Sega CD. The story follows Sonic the Hedgehog as he attempts to save an extraterrestrial body, Little Planet, from Doctor Robotnik. As a Sonic the Hedgehog series platformer, Sonic runs and jumps through several themed levels while collecting rings and defeating robots. Sonic CD is distinguished from other Sonic games by its time travel feature, a key aspect to the story and gameplay. By traveling through time, players can access different versions of stages, featuring alternative layouts, music, and graphics.
Sonic the Hedgehog CD | |
---|---|
North American cover art | |
Developer(s) | Sonic Team |
Publisher(s) | Sega |
Director(s) | Naoto Ohshima |
Producer(s) |
|
Programmer(s) | Matsuhide Mizoguchi |
Artist(s) | Hiroyuki Kawaguchi |
Composer(s) |
|
Series | Sonic the Hedgehog |
Platform(s) | Sega CD, Microsoft Windows, GameCube, PlayStation 2, Android, PlayStation 3, Xbox 360, iOS, Apple TV |
Release | |
Genre(s) | Platform |
Mode(s) | Single-player |
The Sega CD's flagship game, Sonic CD was conceived as an enhanced port of Sonic the Hedgehog 2, but was reworked after lackluster sales of Sonic 2 in Japan. Sonic co-creator Naoto Ohshima directed and Sega developers designed the game to show off the technical capabilities of the Sega CD. The game features the debuts of Amy Rose and Metal Sonic, and includes animated cutscenes produced by Toei Animation. Two soundtracks were composed for the game: the original score was composed by Naofumi Hataya and Masafumi Ogata, while the North American score was composed Spencer Nilsen, David Young and Mark "Sterling" Crew.
Sonic CD is often called one of the best games in the Sonic series and the platform game genre. Reviewers praised its exceptional size, music, and the time travel feature, although some also believed the game did not use the Sega CD's capabilities to its fullest. It sold over 1.5 million copies, making it the Sega CD's bestseller. The game was ported to Windows as part of the Sega PC brand in 1996, and to PlayStation 2 and GameCube as part of Sonic Gems Collection in 2005. A remastered version, developed by Christian Whitehead using the Retro Engine, was released for various platforms and mobile devices in 2011.
Gameplay
Sonic CD is a side-scrolling platform game similar to the original Sonic the Hedgehog. Players control Sonic the Hedgehog as he ventures to stop his nemesis Doctor Robotnik from obtaining the magical Time Stones and conquering Little Planet.[1] Like previous games, Sonic can destroy enemies and objects (such as certain walls and television monitors containing power-ups[1]) by rolling into a ball, and collects rings as a form of health. Sonic can also perform a "spin dash" and a "super peel-out" that can increase his speed.[2] The game is split into seven levels called rounds; each round is split into three zones, the third of which culminates in a boss fight with Robotnik. Players start with three lives, which are lost when they suffer any type of damage without rings in their possession; losing all lives results in a game over.[3][4]
Sonic CD is differentiated from other Sonic games through its time travel game mechanic, which allows players to access different versions of stages set in the past, present and future.[5] Sonic starts the first two zones in the present, and can travel through time by hitting signs labelled "past" or "future" and maintaining speed for several seconds.[6] By default, future stages depict neglect and decay after Robotnik has conquered Little Planet.[6] Players are encouraged to convert each zone into a "good future", with bright colors, no enemies, and few obstacles.[6] To achieve a good future in each zone, players must travel to the past—a primitive, overgrown landscape—and destroy a hidden transporter where enemy robots spawn. Achieving a good future in every zone unlocks the best possible ending.[2][6] The third zone is always set in the future, its timeline dependent upon whether the player destroyed both transporters.[1]
By finishing a level with more than 50 rings, Sonic can access a special stage, in which he must destroy six UFOs in a pseudo-3D environment within a time limit.[1][5] Time is reduced swiftly if the player runs through water, though a special UFO which appears when time is running out grants extra time if destroyed. If the player destroys all the UFOs before the time runs out, they earn a Time Stone.[4] Collecting all seven Time Stones automatically creates a good future in every zone, and unlocks the best ending.[2] The game also features a time attack mode, where players can replay completed levels in the fastest time possible; a "D.A. Garden", where players can listen to the music of completed zones; and a "Visual Mode", where players can view the opening and closing animations.[7] The game also includes a save feature, which uses the back-up memory of the Sega CD.[4]:20
Plot
Set between Sonic the Hedgehog (1991) and Sonic the Hedgehog 2 (1992),[8] Sonic CD opens with Sonic journeying to Never Lake, where an extraterrestrial body, Little Planet, appears in the last month of every year. Sonic's nemesis Dr. Robotnik has tethered the planet to a mountain and begun transforming it into a giant fortress with his robot army. Robotnik seeks the Time Stones, seven jewels capable of altering the passage of time. Sonic ventures into the planet, followed by the besotted Amy Rose, his self-proclaimed girlfriend.[lower-alpha 2] Robotnik dispatches his top robotic enforcer, Metal Sonic, who kidnaps Amy to lure Sonic into danger. Sonic clashes with Robotnik and Metal Sonic and uses time travel to stop Robotnik.
After racing and defeating Metal Sonic in Stardust Speedway and saving Amy, Sonic fights and defeats Robotnik in his base. Two endings exist, depending on whether or not the player collected the Time Stones or achieved a good future in each level. In one ending, Little Planet is returned to its rightful state and leaves Never Lake; in the other, Little Planet leaves Never Lake, but Robotnik uses the Time Stones to retake it and the player is urged to try again and free Little Planet forever.
Development
Background and conception
The original Sonic the Hedgehog (1991) was developed by Sonic Team at Sega. It was a major commercial success and positioned Sega as Nintendo's main rival in the console market.[9] Lead programmer Yuji Naka, dissatisfied with Sega of Japan's rigid corporate policies, moved with several members of Sonic Team to the United States to develop Sonic the Hedgehog 2 with Sega Technical Institute (STI).[10][11] Meanwhile, Sega planned to release the Sega CD add-on for its Genesis, and wanted a Sonic game that would demonstrate its more advanced features. Sonic character designer Naoto Ohshima was Sonic CD's director; the remainder of the team comprised Sega staff who had developed The Revenge of Shinobi, Golden Axe 2, and Streets of Rage. The team built Sonic CD using the original Sonic the Hedgehog code as a base.[12]
The game was conceived as an enhanced port of Sonic 2 for the Sega CD. At this point, it was codenamed Super Sonic[13] and would feature additional levels, a fully orchestrated soundtrack, sprite-scaling effects, and animated cutscenes.[13][14] Meager sales of Sonic 2 in Japan and the team having its own vision resulted in the reworking of the port.[12][15] It was titled CD Sonic the Hedgehog first[16] before being renamed Sonic CD.[15] Ohshima does not consider Sonic CD a sequel to the previous two Sonic games, although artist Yasushi Yamaguchi said players may assume that its story is set between Sonic the Hedgehog and Sonic 2.[17]
Design
Sonic the Hedgehog had a balance on speed and platforming; STI built on the speed with Sonic 2's more focused level designs. However, Ohshima's team sought to focus on the platforming and exploration aspects.[12] Ohshima said, "our ideas were to make the world and setting larger, and to add more replayability, so it would be something you could enjoy playing for a long time."[17] According to artist Kazuyuki Hoshino, because it was a Sega CD game, the team wanted Sonic CD to stand out compared to previous Sonic games. Visually, the game was designed to resemble CG imagery; the Sonic sprite on the title screen was based on a Sonic figurine by Taku Makino that the team photographed and scanned.[17]
Sonic CD marks the debuts of Amy Rose and Metal Sonic, both designed by Hoshino. Although Hoshino created Amy's in-game graphics, many staff members contributed ideas to her design. Her headband and trainer shoes reflected Ohshima's tastes while her mannerisms reflected the traits Hoshino looked for in women at the time. Hoshino designed Metal Sonic in response to Ohshima wanting a strong rival for Sonic. Hoshino had a clear image of Metal Sonic in his mind from the moment he was briefed, and his design emerged after only a few sketches. The character graphics were created using Sega's proprietary graphics system for the Genesis, the "Sega Digitizer MK-III", featuring a bitmap and animation editor. The team mostly used Macintosh IIcis. Graphics data was stored on 3.5-inch floppy disks, which were handed to the programmer to work into the game.[18] Though Naka was not directly involved with Sonic CD, he exchanged design ideas with Ohshima.[19]
Ohshima cited Back to the Future as an influence on the time travel.[19] The developers designed four variants of each stage (one for each time period).[20] Ohshima hoped for the time period to change instantly with a "sonic boom" effect, but the programmers argued this was impossible and produced a loading sequence instead.[19] Sega did not pressure the team developing Sonic CD as much as the one developing Sonic 2. Ohshima felt this was because Sonic CD is not a numbered sequel; he considered it a recreation of the original game.[19] The total game data of Sonic CD is 21 megabytes (MB), compared to Sonic 2's 1 MB.[12] The game includes animated cutscenes produced by Toei Animation;[21] the team used a format that provided uncompressed imagery to the video display processor, which allowed for superior results in contrast to the Cinepak compression used for other Sega CD games.[12] The special stages feature Mode 7-like background plane manipulation effects.[22] Time constraints led to one of the levels being cut.[20]
Music
The Japanese soundtrack was composed by Naofumi Hataya and Masafumi Ogata, who had worked together on the 8-bit version of Sonic the Hedgehog 2. The game features two songs: "Sonic - You Can Do Anything", often referred to as "Toot Toot Sonic Warrior",[23] composed by Ogata and originally written for Sonic the Hedgehog 2, and "Cosmic Eternity - Believe in Yourself", composed by Hataya. Both are sung by Keiko Utoku.[24] The composition team drew inspiration from club music, such as house and techno, while Hataya cited C+C Music Factory, Frankie Knuckles, and the KLF as influences.[25]
Release and localization
Sonic CD was released in Japan on September 23, 1993,[26] and Europe in October 1993.[2] Sega of America delayed the game for two months to have a new soundtrack written and produced by Spencer Nilsen and David Young of Sega Multimedia Studio,[27] with select tracks written and produced by former Santana keyboardist Mark "Sterling" Crew.[28][29] Crew's tracks feature fellow Santana member Armando Peraza as percussionist.[30] According to Nilsen, Sega believed it needed a more "rich and complex" soundtrack.[31] The tracks in the "Past" stages could not be replaced as they were sequenced PCM audio tracks rather than streamed Mixed Mode CD audio.[32] "You Can Do Anything" was replaced with "Sonic Boom", composed by Nilsen and performed by the female vocal group Pastiche.[31][33] The game was released in North America in November 1993.[34] Sonic CD was the flagship Sega CD game and the system's only Sonic game.[35] An enhanced version of the original Sonic the Hedgehog and a Sonic-themed localization of Popful Mail were canceled.[36][37]
Rereleases
Two versions of Sonic CD were released for Windows: one in 1995 for Pentium processors, and another in 1996 for DirectX.[12] The Pentium version was only bundled with new computers and never sold in stores; Sega worked with Intel to make the game work properly.[12] The DirectX version was released under the Sega PC brand[38] and distributed by SoftKey in North America on July 8[39] and in Japan on August 9.[38] This version is mostly identical to the original release,[40] but loading screens were added[12] and it is only compatible with older versions of Windows.[41] Both Windows versions use the North American soundtrack.[12]
The 1996 Windows version was ported to the GameCube and PlayStation 2 in August 2005 for Sonic Gems Collection.[12][42] This port uses the original soundtrack in Japan and the North American soundtrack elsewhere.[43][33] The ports introduced some graphical problems, such as a blurry anti-flicker presentation,[12] but the opening animation is presented in a higher quality fullscreen view.[44]
In 2009, independent programmer Christian Whitehead produced a proof-of-concept video of a remastered version of the game, using his Retro Engine, running on iOS.[45] Sega released this version in 2011 for Xbox 360, PlayStation 3, iOS, Android, and PC, with assistance from Blit Software. The remaster features enhancements such as widescreen graphics, fine-tuned collision detection to make time traveling more consistent, spin dash physics from Sonic the Hedgehog 2, both the Japanese and North American soundtracks, the ability to unlock Tails as a playable character, and achievement and trophy support.[46][47][48][49] Whitehead also designed two original stages, but they were excluded as Sega wanted to keep the game faithful to the original release.[50] The remaster was not released on the Wii as it exceeded the WiiWare download size.[51]
Reception
Publication | Score |
---|---|
CVG | 85/100[2] |
EGM | 9, 9, 8, 8[52][lower-alpha 3] |
GamePro | 5/5[53] |
Electronic Games | 92%[1] |
Sega Magazine | 87/100[3] |
Sega Pro | 90%[5] |
Sega Force Mega | 85%[54] |
Entertainment Weekly | A-[55] |
Publication | Award |
---|---|
Electronic Gaming Monthly | Best Sega CD Game of 1993[56] |
Sonic CD received critical acclaim.[1][5][56] The Sega CD version sold more than 1.5 million copies, making it the system's bestseller.[57][58]
The presentation, visuals, and audio were praised. Computer and Video Games wrote that, although Sonic CD did not use the Sega CD's capabilities to its fullest, the game's graphics and sound were still excellent, calling the music "from the likes of 2Unlimited and Bizarre Inc".[2] Electronic Games said that the game looked similar to older games and used the Sega CD's special features minimally, but this did not detract from the quality. The music was singled out as making Sonic CD "stand above the crowd"; the reviewer wrote that it helped add richness to the game.[1] The reviewers of Electronic Gaming Monthly (EGM) praised the game's animated cinematics and sound, but noted frame rate drops during special stages.[52] Retrospective opinions of the presentation have also been positive. IGN praised its vibrant colors and felt the game looked nice,[59] and GamesRadar thought its music stood the test of time, writing: "What must've dated very quickly in the 1990s is somehow totally fresh today."[22]
Critics were divided over the change of soundtrack in the North American versions. GameFan, which had given the Japanese version of Sonic CD a score of 100%, lambasted the change.[60][61] GameFan editor Dave Halverson called the change "an atrocity that remains the biggest injustice in localization history".[62] The reviewer for GamesRadar said he shut his GameCube off in disgust when he realized Sonic Gems Collection used the American soundtrack.[22] In a 2008 interview, Nilsen said "I think critics were looking for a way to bash the game... it was like we replaced the music for Star Wars after the movie had been out for a while."[31]
The gameplay was also widely praised. EGM admired the diverse levels and felt the time travel added depth.[52] Electronic Games wrote that Sonic CD played as well as previous Sonic games, and that the time travel—coupled with large levels rich with secrets and Super Mario Kart-like special stages—added replayability.[1] Sega Pro also noted the expanded environments and the replay value travel added by the time travel, writing that "the more you play Sonic CD the better it gets", but felt the game was too easy.[5] In its debut issue, Sega Magazine said Sonic CD was "potentially a classic".[3] GameSpot singled out the "interesting level design and the time-travelling gameplay" as a major selling point, saying it provided a unique take on the classic Sonic formula.[6]
Critics wrote that Sonic CD was one of the best Sega CD games. Electronic Games called it a must-have,[1] and Sega Pro said it was "brilliant", imaginative and worth more than its price.[5] Destructoid described it as "a hallmark of excellence", creative, strange, and exciting, and said that "to miss Sonic CD would be to miss some of the franchise's best".[63]
Reception to later versions of Sonic CD varied. GameSpot considered the 1996 Windows version inferior, criticizing its technical performance and "tedious and monotonous" gameplay. The reviewer wrote that "those who have played Sonic on a Sega game system will find nothing new here" and that it was not worth its $50 price.[40] Reviews of the version in Sonic Gems Collection were favorable. IGN remembered Sonic CD as one of the best things about the Sega CD and called it a standout for the compilation, and a major selling point.[43] Eurogamer wrote: "Rejoice for Sonic CD... Just don't rejoice for anything else [in Sonic Gems Collection], because it's mostly rubbish."[64] According to Metacritic, the 2011 console version received "generally favorable reviews",[65][66] while the iOS version received "universal acclaim".[67] Sonic CD is frequently named among the best Sonic games and platform games.[68][69][70][71][72] In 1997, EGM named it the 17th best console game of all time, citing the bonus levels and animated intro.[73]
Legacy
The story of Sonic CD was adapted in the twenty-fifth issue of Archie Comics' Sonic the Hedgehog comic book series. The adaptation featured some changes to the story, such as Tails being an important character and Metal Sonic having the ability to talk.[74] British publisher Fleetway Publications published their own adaptation in Sonic the Comic.[75] The final issue of Archie's comic, #290 (December 2016), also featured a retelling of the game's story.[76]
Two characters introduced in the game, Amy Rose and Metal Sonic, became recurring characters in the Sonic series. Metal Sonic appeared as a major antagonist in Knuckles' Chaotix (1995),[77] Sonic Heroes (2003),[78] and Sonic the Hedgehog 4: Episode II (2012), whose story heavily connects to Sonic CD.[79] Amy Rose most notably appears in Sonic Adventure.[80] The Sonic CD animated sequences were included as bonuses in the compilation Sonic Jam (1997), and "Sonic Boom" was used as one of Sonic's themes in Super Smash Bros. Brawl (2008).[31][81]
In 2011, for the Sonic franchise's twentieth anniversary, Sega released Sonic Generations, which includes remakes of various Sonic stages. Both versions feature a re-imagined version of the boss battle against Metal Sonic.[82] The 2017 game Sonic Mania, produced for the series' twenty-fifth anniversary, features updated versions of Sonic CD's Metallic Madness and Stardust Speedway levels, including a boss battle against Metal Sonic.[83][84][85]
Notes
- Japanese: ソニック・ザ・ヘッジホッグ
CD , Hepburn: Sonikku za Hejjihoggu Shī Dī - In the North American manual, Amy is incorrectly identified as Princess Sally, a character from Archie's Sonic the Hedgehog comic book.
- EGM provided four scores from individual reviewers.
References
- Camron, Marc (December 1993). "CD Gallery". Electronic Games. Vol. 2 no. 3. p. 140. Retrieved December 19, 2017.
- Rand, Paul (November 1993). "Review: Sonic CD" (PDF). Computer and Video Games. No. 144. p. 87. Retrieved August 29, 2017.
- "Review: Sonic CD" (PDF). Sega Magazine. No. 1. January 1994.
- Sonic Team (November 1993). Sonic the Hedgehog CD instruction manual. Sega.
- "Sonic the Hedgehog CD". Sega Pro (Review). November 1993. pp. 38–40. Retrieved February 8, 2018.
- Kemps, Heidi (January 3, 2012). "Sonic CD Review". GameSpot. Retrieved February 8, 2018.
- "Sonic CD PS3 Cheats". Game Revolution. January 5, 2012. Archived from the original on April 5, 2019. Retrieved February 10, 2018.
- Sandler, Corey (1994). Sonic The Hedgehog 3 Full Color Action. Brady Publishing. p. 72. ISBN 1-566-86-146-2.
A little bit of history: Sonic CD was released originally in Japan and takes place somewhere between Sonic 1 and Sonic 2.
- "This Month in Gaming History". Game Informer. Vol. 12 no. 105. January 2002. p. 117.
- Smith, Sean (June 2006). "Company Profile: Sonic Team". Retro Gamer. No. 26. Imagine Publishing. pp. 24–29. Retrieved October 12, 2019.
- Day, Ashley (March 2007). "Company Profile: Sega Technical Institute". Retro Gamer. No. 36. Imagine Publishing. pp. 28–33.
- Linneman, John (April 8, 2018). "DF Retro: Sonic CD - under-appreciated but still brilliant today". Eurogamer. Gamer Network. Retrieved April 8, 2018.
- "Super Sonic on CD". MegaTech. 1992.
- "Mega CD Sonic Update". Mean Machines. p. 191.
- Kai, Norton (April 1993). "Sonic CD Splits Up". Sega Force. No. 16. p. 12.
- "CD Sonic the Hedgehog". Electronic Gaming Monthly. No. 44. March 1993. p. 122. Retrieved October 12, 2019.
- "Sonic CD – Developer Interview Collection". Shmuplations. March 24, 2020. Retrieved March 24, 2020.
- Stuart, Keith (2014). "Interview with Kazuyuki Hoshino, Art Director". Sega Mega Drive/Genesis: Collected Works. Read-Only Memory. pp. 289–290. ISBN 9780957576810.
- Sheffield, Brandon (December 4, 2009). "Out of the Blue: Naoto Ohshima Speaks". Gamasutra. Archived from the original on April 24, 2016. Retrieved April 15, 2017.
- "Sega's Yuji Naka Talks!". GameSpy. IGN. Archived from the original on February 23, 2017. Retrieved June 16, 2017.
- "Sonic the Hedgehog CD". The History of Sonic the Hedgehog. Pix 'n Love. p. 130.
- Towell, Justin (December 16, 2011). "Sonic CD review". GamesRadar. Archived from the original on November 17, 2015. Retrieved December 20, 2017.
- McFerran, Damien. "How Sega can save its mascot with Sonic Mania". Red Bull. Retrieved June 14, 2017.
- "Sonic Joins the Digital Revolution". Electronic Gaming Monthly. Vol. 6 no. 8. August 1993. p. 92.
- Stuart, Keith (2014). "Interview with Naofumi Hataya". Sega Mega Drive/Genesis: Collected Works. Read-Only Memory. p. 312. ISBN 9780957576810.
- "[セガハード大百科] メガCD対応ソフトウェア". Sega. Archived from the original on December 16, 2009. Retrieved May 30, 2015.CS1 maint: unfit URL (link)
- "Sega-16 – Interview: Spencer Nilsen (Composer)". Retrieved January 17, 2021.
- "Sterling Crew". Discogs. Retrieved January 17, 2021.
- "Ending for Sonic the Hedgehog CD (Sega CD)". www.vgmuseum.com. Retrieved January 17, 2021.
- "Q&A: A Conversation with Armando Peraza". salsaweb.com. Archived from the original on December 24, 2008. Retrieved January 17, 2021.
- Horowitz, Ken (December 9, 2008). "Interview: Spencer Nilsen (Composer)". Sega-16. Archived from the original on May 12, 2018. Retrieved June 28, 2017.
- Elston, Brett (April 28, 2009). "17 videogame soundtracks ahead of their time". GamesRadar. Archived from the original on March 10, 2016. Retrieved April 15, 2017.
- Gibson, Ellie. "Sonic Gems line-up in doubt". Eurogamer. Archived from the original on March 4, 2016. Retrieved April 15, 2017.
- "Sonic the Hedgehog CD". GamePro. Vol. 6 no. 1.
- Elston, Brett. "The rise, fall and deafening crash of Sonic the Hedgehog". GamesRadar. p. 1. Retrieved February 10, 2018.
- "Coming Attractions". MegaPlay. Vol. 3 no. 11. August 1992. p. 30.
- "Sonic's Dad!". Electronic Gaming Monthly. No. 49. August 1993. p. 71. Retrieved October 12, 2019.
- Sega. "Windows". Sonic Channel. Archived from the original on October 24, 2016. Retrieved April 17, 2017.
- "Sonic CD [1996] - PC". IGN. Ziff Davis. Retrieved August 29, 2017.
- Blevins, Tal (September 19, 1996). "Sonic CD (1995) Review". GameSpot. Archived from the original on May 18, 2017. Retrieved April 21, 2017.
- Procter, Lewie. "No Disc Required: Sonic CD Heading To PC". Rock, Paper, Shotgun. Archived from the original on May 17, 2017. Retrieved April 15, 2017.
- Sketcz (October 22, 2009). "Blog: I like burning hedgehogs". Hardcore Gaming 101. Retrieved February 24, 2018.
- "Sonic Gems Collection - IGN". IGN. Archived from the original on April 18, 2016. Retrieved November 20, 2016.
- "Sonic Gems Collection". Nintendo Power. No. 195. Future plc. September 2005. p. 40.
- Sigl, Rainer (February 1, 2015). "Lieblingsspiele 2.0: Die bewundernswerte Kunst der Fan-Remakes". Der Standard. Archived from the original on November 24, 2016.
- "Proof Of Concept Of Enhanced Sonic CD On iPhone | WatchPlayRead - "It's What We Do!"". WatchPlayRead. July 28, 2009. Archived from the original on May 3, 2012. Retrieved November 23, 2011.
- "Sonic CD coming to XBLA, PSN and more this holiday | WatchPlayRead - "It's What We Do!"". WatchPlayRead. August 25, 2011. Archived from the original on May 4, 2012. Retrieved November 23, 2011.
- "SEGA Blog | Sonic CD Spins Onto Tablets at GameStop". Blogs.sega.com. Archived from the original on December 1, 2011. Retrieved November 23, 2011.
- "SEGA Blog | #SegaPAX – Sonic CD Announced!". Blogs.sega.com. August 25, 2011. Archived from the original on October 19, 2011. Retrieved November 23, 2011.
- Nelson, Jared. "Play 'Sonic The Hedgehog 2' Hidden Palace Zone in Prototype Form with this New Easter Egg". TouchArcade. Retrieved June 23, 2017.
- Holmes, Jonathan. "Sonic CD is too big to come to WiiWare". Destructoid. Archived from the original on September 10, 2015. Retrieved April 16, 2017.
- "Review Crew: Sonic CD". Electronic Gaming Monthly. Vol. 6 no. 11. November 1992. p. 48. Retrieved December 19, 2017.
- The Unknown Gamer (January 1994). "Sega CD ProReview: Sonic the Hedgehog CD" (PDF). GamePro. pp. 64–68.
- Chris; Mark (January 1994). "Sonic the Hedgehog CD". Sega Force Mega. Vol. 2 no. 7. pp. 102–4.
- https://ew.com/article/1994/02/11/sonic-cd-sonic-chaos-sonic-spinball-sonic-3/
- "Electronic Gaming Monthly's Buyer's Guide". 1994. Cite magazine requires
|magazine=
(help) - Official Gallup UK Mega-CD sales chart, February 1994, published in Mega issue 17
- Records, Guinness World (2015). Guinness World Records 2016: Gamer's Edition. ISBN 978-1910561096.
- DeVries, Jack (December 15, 2011). "Sonic CD Review". IGN. Archived from the original on November 4, 2016. Retrieved December 20, 2017.
- Skid; Sgt. Gamer; K. Lee; The Enquirer (November 1993). "Sonic CD - Sega CD - 1 Player". GameFan. p. 22. Retrieved January 1, 2020.
- Skid; Sgt. Gamer; K. Lee; Brody (January 1994). "Sonic CD Re-Review - Sega - Sega CD - 1 Player". GameFan. p. 18. Retrieved January 1, 2020.
- Elston, Brett (April 28, 2009). "17 videogame soundtracks ahead of their time". GamesRadar. p. 2. Archived from the original on April 5, 2019. Retrieved February 8, 2018.
- North, Dale. "Review: Sonic CD". Destructoid. Retrieved February 9, 2018.
- Bramwell, Tom (October 6, 2005). "Sonic Gems Collection". Eurogamer. Archived from the original on June 22, 2018. Retrieved February 8, 2018.
- "Sonic CD for PlayStation 3 Reviews". Metacritic. Retrieved February 8, 2018.
- "Sonic CD for Xbox 360 Reviews". Metacritic. Retrieved February 8, 2018.
- "Sonic CD for iPhone/iPad Reviews". Metacritic. Archived from the original on August 29, 2016. Retrieved August 25, 2016.
- GamesRadar Staff (October 29, 2013). "The best Sonic games of all time". GamesRadar. p. 3. Archived from the original on March 22, 2017. Retrieved February 8, 2018.
- USgamer Team (August 8, 2017). "Gotta Go Fast: Ranking All of The Sonic The Hedgehog Games". USgamer. Archived from the original on August 21, 2017. Retrieved February 5, 2018.
- Towell, Justin (February 6, 2013). "Why Sonic CD is one of the greatest games ever made". GamesRadar. Archived from the original on May 17, 2017. Retrieved April 15, 2017.
- Noble, McKinley. "The 20 Best Platformers: 1989 to 2009". GamePro. Archived from the original on January 28, 2010.
- "25 Best iPhone and iPad Games of 2011". Metacritic. December 31, 2011. Archived from the original on December 27, 2012. Retrieved January 9, 2013.
- "100 Best Games of All Time". Electronic Gaming Monthly. No. 100. Ziff Davis. November 1997. p. 148. Note: Contrary to the title, the intro to the article (on page 100) explicitly states that the list covers console video games only, meaning PC games and arcade games were not eligible.
- Flynn, Ian; Penders, Ken; Gallagher, Mike; Kanterovich, Mike (July 18, 2012). Sonic: The Games - Classic. Archie Comics. ISBN 978-1619883437. Retrieved February 11, 2018 – via Google Books.
- "Paper with Attitude". GamesTM. 2009.
- Sims, Chris (December 27, 2016). "Meet Amy Rose For The First Time (Again) In 'Sonic the Hedgehog' #290 [Preview]". ComicsAlliance. Archived from the original on May 17, 2017. Retrieved April 16, 2017.
- "Chaos Over Knuckles". Mean Machines Sega. No. 29. March 1995. p. 08. Retrieved October 12, 2019.
- Sonic Team USA (December 30, 2003). Sonic Heroes. Sega. Level/area: Metal Overlord.
- Fletcher, JC (April 10, 2012). "Sonic 4 Episode 2 'locks on' to Episode 1 to add Metal Sonic". Engadget. Archived from the original on October 16, 2018. Retrieved February 10, 2018.
- Gies, Arthur (September 23, 2010). "Sonic Adventure Review". IGN. Archived from the original on March 6, 2013. Retrieved April 20, 2013.
- "Full Song List with Secret Songs - Smash Bros. DOJO!!". Retrieved January 3, 2021 – via smashbros.com.
- Thomas, Kurt (July 13, 2011). "Metal Sonic Charges Into Sonic Generations". Game Informer. Archived from the original on September 13, 2011. Retrieved November 23, 2011.
- Kemps, Heidi (August 14, 2017). "Sonic Mania Review". IGN. Archived from the original on August 15, 2017. Retrieved August 14, 2017.
- Sampson, Aaron (August 14, 2017). "Sonic Mania Metallic Madness Zone Act 1 - Gameplay". GameSpot. Retrieved February 8, 2018.
- "Sonic Mania - Fighting Metal Sonic". IGN. August 16, 2017. Retrieved February 8, 2018.