Sonic Underground title card
|Created by||Jean Cheville|
|Directed by||Marc Boreal
|Voices of||Jaleel White
|Theme music composer||Robby London
|Opening theme||"Sonic Underground"|
|Country of origin||United States
|No. of episodes||40|
|Executive producer(s)||Andy Heyward
|Running time||21 minutes|
Les Studios Tex
DiC Productions L.P.
|Distributor||Buena Vista International Television
Vivendi Entertainment (DVD and Home Media)
DHX Media (Current)
|Original network||TF1 (France)
First-run syndication (U.S.)
|Original release||6 January– 22 October 1999|
|Related shows||Adventures of Sonic the Hedgehog
Sonic the Hedgehog
Sonic Underground is an animated series co-produced by TF1, DiC Entertainment (which was owned by Disney at the time) and Les Studios Tex. It is the third Sonic the Hedgehog animated series, and also the last one produced by DiC; it follows a main plot separate from all other Sonic the Hedgehog media, where Sonic had two siblings, Sonia and Manic, that were collectively part of a royal family who were forced to separate from their mother, Queen Aleena, upon Robotnik's takeover of Mobius due to a prophecy told by the Oracle of Delphius. It first premiered in France on 6 January 1999 on TF1, and then premiered in the United Kingdom on 2 May 1999 on ITV and finally in the United States in syndication on 30 August 1999 and ended on 22 October 1999. It was the first Sonic the Hedgehog television series to be sold on the iTunes Store. The show ran only for one season consisting of forty episodes.
The show takes place in a separate canon and continuity than any other Sonic the Hedgehog media. Queen Aleena, the former ruler of Mobius, was overthrown by Dr. Robotnik and his lackeys Sleet and Dingo. Robotnik seized control of the planet and forced Queen Aleena into hiding. To preserve the dynasty, Queen Aleena separated her three children: Sonic, Manic, and Sonia after the Oracle of Delphius told her of a prophecy, proclaiming that one day, Queen Aleena would reunite with her children to form the "Council of Four," and overthrow Robotnik. Meanwhile, Dr. Robotnik did his best to set up an autocratic government, and legally turned anyone who stood against him into robots devoid of freewill, and forced the nobles into paying large amounts of money to him as tribute.
When Sonic, Manic, and Sonia grew up, the Oracle of Delphius revealed the prophecy to them. After that, Sonic, Manic, and Sonia decided to go on a quest, searching throughout Mobius for Queen Aleena. Dr. Robotnik, with the assistance of the Swat-Bots and his bounty hunters Sleet and Dingo, tries constantly to capture the royal hedgehogs and prevent the prophecy from being fulfilled.
The Oracle of Delphius has assigned the three siblings powerful "medallions" that can change into musical instruments, and can also be used as weapons. Sonic's medallion is an electric guitar, Sonia's medallion is a keyboard that functions as a smoke machine, and Manic's medallion is a drumset that can be used as an "earth controller" with cymbals that can deflect laserfire. All of the medallions can be used as laser guns. The three use the amulets not only to fight Robotnik's forces but to also as instruments for their underground rock band, "Sonic Underground."
- Sonic the Hedgehog: The lead singer of many songs performed by the Sonic Underground. His medallion turns into a guitar, which can fire laser blasts. As fast as the speed of sound, Sonic can easily outrun danger. He is a big fan of chili dogs. He also has hydrophobia, being terrified of water as he cannot swim. Sonic wears anti-gravity sneakers that allow him to hover over the ground while running. He was voiced by Jaleel White, and his singing voice was done by Sam Vincent.
- Sonia the Hedgehog: The only female hedgehog member of the Sonic Underground and the sister of Sonic and Manic. Unlike her brothers, she was raised by an aristocratic foster family, giving her an upper class mentality. She hates getting dirty, is skilled at gymnastics and karate, and possesses superhuman strength, a photographic memory, and the ability to spin in a cyclonic manner similar to the Tasmanian Devil and Espio the Chameleon. Her medallion turns into a keyboard, which can fire laser blasts from one end, or create a pink mist when the keys are played. Sonia has a pink motorcycle which can travel as fast as Sonic's running and Manic's hover board (it was destroyed in the 36th episode). She also is the one that does research on Robotnik's plans and provides the technological innovation for the Sonic Underground. Of the siblings, Sonia is the only one to be seen involved in any romance, displaying feelings for her childhood friend Bartleby, despite his snobbishness, as well as other men encountered in her travels. Among these is Knuckles, whom she develops an attraction to during the series' Flying Fortress saga. She was also voiced by Jaleel White, and her singing voice was done by Louise Vallance.
- Manic the Hedgehog: He is a calculating and sarcastic hedgehog that was raised by thieves, and is a master of their trade. When Manic met his siblings, they disapproved of his thieving tendencies, but his skills as a lock-pick were greatly appreciated. Manic possesses neither Sonic's speed nor Sonia's spin-attack, thus making him the only member of the Sonic Underground who relies on entirely on his medallion for superpowers of his own. Despite his lack of superpowers, his thieving skills proves himself extremely useful to the group from time to time. Manic is the drummer of the Sonic Underground. His medallion turns into drums, which can cause earthquakes; the Oracle of Delphius claims that his drums are the most powerful instruments of the three. He also has a hover board that is as fast as Sonic's running and Sonia's motorcycle. His medallion's string is blue. Like Sonic and Sonia, he was voiced by Jaleel White, and his singing voice was done by Tyley Ross.
- Dr. Robotnik: He is the evil dictator of Mobius, renamed Robotropolis under his rule, having conquered it with his army of Swatbots. He captures and roboticizes anyone who opposes him, transforming them into robotic servants. Though he is depicted as a bumbling villain, one of his goals is to find Sanctuary - where Freedom Fighters hide their children - and exterminate all the children in it. Robotnik's primary minions are Sleet and Dingo, two bounty hunters that will do anything to capture Sonic and his siblings. His voice was provided by Garry Chalk.
- Sleet: One of Robotnik's canine bounty hunters. This cunning wolf leads the bumbling Dingo about on missions to capture the hedgehogs. He has a morphing device that can transform Dingo into anything he wishes. He is constantly being crushed by Dingo and is usually the one who suffers the most from their combined failures. He was voiced by Maurice LaMarche.
- Dingo: One of Robotnik's canine bounty hunters. Dingo is a huge, muscle-bound blonde canid with an Australian accent, and is also very ignorant. He is partially roboticised in his hands and his left leg from the knee down, which is never explained. He has a relentless crush on Sonia, but remains fiercely loyal to his partner, Sleet. He was voiced by Peter Wilds.
- Queen Aleena Hedgehog: The mother of the Sonic Underground group and former ruler of Mobius before Robotnik's takeover. She had to give them up in order for the prophecy to become true. She spends the series on the run from her own children, until the time is right to reveal herself. Her character has many allies, including the Oracle of Delphius and Knuckles. She also does a bit of narrating in the start of every episode. She is voiced by Gail Webster.
- Knuckles the Echidna: The guardian of one of the Chaos Emeralds and the Floating Island, and an acquaintance of Queen Aleena's. He is very protective of his island home, and has set many traps about the island. He has a pet dinosaur called Chomps, and like his game incarnation is shown to be somewhat gullible. His great-grandfather Athair warns him that he must stay on the island in order to play his part in the freedom of Mobius. He turned against the Hedgehogs twice-first being tricked into thinking they were thieves and later thinking that it was the only way to save their planet-but came around and worked with them against the threat of Robotnik and his henchmen. During the Flying Fortress arc, he showed signs of a growing affection for Sonia, including a particular guilt over the prospect of betraying her. He was voiced by Brian Drummond.
- Oracle of Delphius: An odd, wart-covered, reptilian anteater in a cloak. The Oracle prophesied that when Robotnik invaded Mobius, Aleena and her children would form the Council of Four to overthrow Robotnik and free Mobius. The Oracle lives in a cave somewhere in a cold region of Mobius, and is quite good at making chili dogs. He is named after the Oracle at Delphi. He is voiced by Maurice LaMarche.
- Sir Bartleby Montclair: A posh, cowardly mink who is one of Robotropolis' richest aristocrats. Bartleby is Sonia's fiancé. He dislikes Dr. Robotnik and is often forced to fund Robotnik's schemes - although in secret he still supports Aleena. He speaks with an upper-class English accent. He is voiced by Philip Maurice Hayes.
- Cyrus: Cyrus is a lion and a technician for the Freedom Fighters. He is an old friend of Sonic. In his first appearance he was working as a spy for Robotnik, but quit upon discovering that the Freedom Fighters' Sanctuary was a hideout for their children. Cyrus's father was roboticized. His voice was provided by Ian James Corlett.
- Trevor: Trevor is a mouse who is a friend of the royal siblings and Cyrus. He dresses like a hippie. He is an ace pilot and helps build and fix mechanical equipment. He is voiced by Matt Hill.
|#||Episode title||Episode song||Written by||Original air date (France)||Original air date (United States)|
|1||"Wedding Bell Blues"||When Tomorrow Comes||Ben Hurst and Pat Allee||6 January 1999||4 October 1999|
|Dr. Robotnik plots to become the king of Mobius. His first attempt was to marry Queen Aleena, which did not work due to the limited amount of money Robotnik had. His second attempt was to adopt Queen Aleena's daughter Sonia. In order to do this, he had Sleet and Dingo capture all of the hedgehogs and give Sonia to Robotnik so he could adopt her. Robotnik was almost successful until Queen Aleena demanded Robotnik not to adopt her.|
|2||"To Catch a Queen"||Have You Got the 411?||Doug Booth||10 January 1999||31 August 1999|
|Argus, the former captain of the Queen's guard, arranges a secret meeting with her but he is soon intercepted by Robotnik's bounty hunters, Sleet and Dingo, who have every intention of feeding the soldier to the Roboticizer. Then Sonic, Sonia, and Manic attempt to rescue him.|
|3||"Mobodoon"||I've Found My Home||Peter Hunzinger||13 January 1999||1 September 1999|
|Evading Sleet and Dingo the hedgehogs find themselves in a town completely untainted by Robotnik where Sonic and his siblings find the people to be nice, and the food is free. After using the Power Stone, the siblings discover that this is where they were born. Manic starts to become attached to the place and reports that this is he wants to stay.|
|4||"The Price of Freedom"||Money Can't Buy||Martha Moran||17 January 1999||2 September 1999|
|Sonia, after getting dirty on one of her missions, drives to East Mobius; Sonic and Manic follow her after receiving news that Queen Aleena had been spotted there. There, Sonia is reunited with an old friend, Mindy LaTour, and her father. Mindy gives Sonia a watch. Unknown to the girls though, the timepiece is a tracking device designed by Robotnik. Sonia finds out, and soon, Mindy's estate is swarming with similar wristwatch-style robots, all being programmed to capture the hedgehogs.|
|5||"Underground Masquerade"||Let the Good Times Roll||Rick Merwin||20 January 1999||3 September 1999|
|Sonic and Sonia become concerned after Manic reportedly begins to "backslide to his old ways" when he discovers a band of thieves led by Max. Sleet and Dingo are plotting to avoid giving the taxes they are collecting to Robotnik. They choose Manic to frame for a theft.|
|6||"Tangled Webs"||Teach the Children, Light the Way||Ben Hurst and Pat Allee||24 January 1999||6 September 1999|
|Sonic meets up with his friend Cyrus. While Sonic believes that Cyrus has joined the Freedom Fighters, he is actually working for Dr. Robotnik. When he finds out that the Freedom Fighters' "sanctuary" is for children he destroys Robotnik's communicator. Sonic, Sonia and Manic try to get him away from Robotnik.|
|7||"The Deepest Fear"||Face Your Fear||Michael Edens and Mark Edens||27 January 1999||7 September 1999|
|On a trip to Port Mobius Sonic, Manic and Sonia are told that ships are sinking due to the Mobian sea-beast Moby Deep. The hedgehogs also meet Captain Squeege who informs them of a scam in which the townspeople must rely on Robotnik for protection from the sea monster. In reality it is Robotnik who is sinking the ships. Sonic is urged to overcome his fear of water and the monster to find the truth and end the fears of the seaside town.|
|8||"Who Do You Think You Are"||We Need to Be Free||Ben Hurst and Pat Allee||31 January 1999||8 September 1999|
|The Sonic Underground arrive in Tashistan in search of the Queen's Journal. Sonia loses her memory and meets Raphi, one of the town's resistance.|
|9||"The Last Resort"||Listen to Your Heart||Michael Edens||3 February 1999||9 September 1999|
|While escaping from Sleet and Dingo, Sonic, Sonia, and Manic come across Lake Valley Resort. Lake Valley Resort is led by Stripes, who believes that making deals with Robotnik is safer than fighting Robotnik. When Robotnik asks if there are any new people staying at Lake Valley Resort, he reveals that Sonic and Manic are there, leaving out Sonia.|
|10||"Come Out Wherever You Are"||Society Girl||Ben Hurst and Pat Allee||7 February 1999||10 September 1999|
|Bartleby, with the aid of Robotnik, invites Sonia to the Debutante Ball. Meanwhile, Robotnik comes out with the predator, an animal-like machine that will capture and robotisize all members of the resistance. When the resistance hijacks the predator, Sonia is chosen to lead the captured members of the resistance to safety.|
|11||"Winner Fakes All"||Built for Speed||Mark Edens||10 February 1999||13 September 1999|
|Robotnik has created a super-fast robot and he's organized a race for the top athletes of Mobius and the robot.|
|12||"A Hedgehog's Home Is Her Castle"||Let's Do It to It||Len Janson||14 February 1999||14 September 1999|
|Sonia inherits a spooky and dilapidated castle and she enjoys the idea of making it the Underground headquarters. They also choose to stay there overnight.|
|13||"Artifact"||You Can't Own Everything||Michael Edens||17 February 1999||15 September 1999|
|In order to raise money for his own cause, Robotnik auctions off artifacts from the lost city of Mobupinchu. But these artifacts are actually bombs, and they are about to go off.|
|14||"Bug!"||Never Give Up||Len Janson||21 February 1999||16 September 1999|
|The Sonic Underground finds a village that has been destroyed by its Freedom Fighter occupants. The Sonic Underground find that it seems to have something to do with Robotnik's flybots which are all over the desert, as Manic finds out when one of them injects him with a mind-control toxin, making him a slave to Dr. Robotnik.|
|15||"Sonic Tonic"||The Fastest Thing Alive||Mark Edens||24 February 1999||17 September 1999|
|Using the essence of a rare plant Robotnik manages to create a potion that could grant Sleet and Dingo the ability to run at the speed of Sonic.|
|16||"Friend or Foe?"||Not Always What They Seem||Kevin Donahue||28 February 1999||20 September 1999|
|The band visit the Floating Island in search of their mother. There they meet Knuckles the Echidna, the island's guardian, who has been falsely told by Sleet and Dingo that the Sonic Underground is after the Chaos Emerald. Knuckles jumps to conclusions and while Knuckles and Sonic battle each other Sleet and Dingo seek to steal the Emerald.|
|17||"Head Games"||Take a Chance||Michael Edens||3 March 1999||21 September 1999|
|Queen Aleena tells Sonic, Sonia, and Manic that they are needed in Speedster Island, where they worship stone heads of Mobian hedgehogs. Sonic, Sonia and Manic discover that Sleet and Dingo are scaring the fish away so people who live on Speedster Island move out. Meanwhile, Bartleby wants to turn Speedster Island into a modern resort for wealthy people, with Sleet and Dingo pretending to help. When Sonic, Sonia, and Manic arrive on Speedster Island, Sleet and Dingo capture the hedgehogs, while breaking the promises he made to Bartleby and the people who live on Speedster Island.|
|18||"When in Rome..."||Where There's a Will, There's a Way||Len Janson||7 March 1999||22 September 1999|
|As a test of the hedgehogs' intellect and wit, the Oracle strips them of their powers and sends them into an alternate, Roman-themed reality where a Sleet-look-alike presides as Emperor.|
|19||"The Jewel in the Crown"||The Cosmic Dance||Mark Edens||10 March 1999||23 September 1999|
|Queen Aleena's Royal Jewel can reportedly trace the location of Queen Aleena. Having apparently found the jewel Sonic, Sonia and Manic think they may have found their mother at last. It is actually a trap to capture Robotnik they've just fallen into.|
|20||"Three Hedgehogs and a Baby"||Being a Kid Is Cool||Len Janson||14 March 1999||24 September 1999|
|While in Mobotropolis Sonic, Sonia and Manic find an abandoned baby hedgehog. While Sonic and Sonia search for its parents Manic is left to look after it and utilizes his mothering instincts. The baby is actually a robot and Robotnik almost uncovers the Freedom Fighters' sanctuary.|
|21||"Dunes Day"||True Blue Friend||Mark Edens||17 March 1999||27 September 1999|
|The Sonic Underground come across a nomadic tribe whilst journeying through the desert. Manic claims to not trust the tribe's leader "Ifyoucan". He sets off to find out the truth and uncovers a shocking secret.|
|22||"Mummy Dearest"||Mummy Wrap||Ben Hurst and Pat Allee||21 March 1999||28 September 1999|
|The Sonic Underground journey through the treacherous Mobian desert as they try to locate a hidden temple filled with prophecies of Robotnik's defeat.|
|23||"Hedgehog in the Iron Mask"||Part of the Problem||Bob Forward||24 March 1999||29 September 1999|
|The Sonic Underground rescue a prisoner from one of Robotnik's towers – a hedgehog wearing a mask. The prisoner claims he is the hedgehogs' uncle and twin brother of Queen Aleena. It is a sinister ploy by Robotnik to split the Sonic Underground up.|
|24||"Six Is a Crowd"||I Can Do That for You||Len Janson||28 March 1999||30 September 1999|
|The hedgehogs visit the Oracle again. He sends them to an alternate dimension where they are tyrannical rulers of Mobius and Robotnik is the leader of the Freedom Fighters. They must defeat their corrupted selves and restore peace to Mobotropolis.|
|25||"Flying Fortress"||No One Is an Island||Mark Edens||31 March 1999||1 October 1999|
|Chaos Emerald Crisis (Part 1 of 3). Robotnik creates a new flying fortress to lay waste to the planet. When the Sonic Underground suspect that a Chaos Emerald is keeping the fortress aloft they head to the Floating Island to enlist the help of Knuckles. Sleet and Dingo steal the Emerald before the group can reach it causing the fortress to fall into the sea.|
|26||"Beginnings"||Someday||Ben Hurst and Pat Allee||4 April 1999||30 August 1999|
|Origins (Part 1 of 3). Queen Aleena Hedgehog tells the story of how Dr. Robotnik took over planet Mobius and how she had to give up her three children Sonic, Sonia, and Manic to fulfill a prophecy that one day the siblings will be able to rise against Robotnik's rule and restore peace to the planet.|
|27||"No Hedgehog Is an Island"||Learn to Overcome||Mark Edens||7 April 1999||5 October 1999|
|Chaos Emerald Crisis (Part 2 of 3). After taking off with the Chaos Emerald, Dingo accidentally breaks it unleashing the chaos energy inside. The Sonic Underground and Knuckles set off to talk to Knuckles' great grandfather Athair for advice on handling the situation. Athair advises them to make an alliance with Robotnik.|
|28||"Getting to Know You"||Working Together in Harmony||Ben Hurst and Pat Allee||11 April 1999||6 October 1999|
|Origins (Part 2 of 3). The newly reunited Sonic Siblings must learn to work as a team if they are to do battle with Robotnik.|
|29||"New Echidna in Town"||The Mobius Stomp||Mark Edens||14 April 1999||7 October 1999|
|Chaos Emerald Crisis (Part 3 of 3). Knuckles bargains with Robotnik in order to recover and repair the Chaos Emerald before Mobius is destroyed but, to acquire the villain's help, the echidna must betray the Hedgehogs. After rescuing his friends from the Roboticizer, Knuckles and the Sonic Underground must now combat Dingo transformed by the chaos energy into a monster.|
|30||"Harmony or Something"||We're All in This Together||Ben Hurst and Pat Allee||18 April 1999||8 October 1999|
|Origins (Part 3 of 3). Sonic, Sonia and Manic go on a mission to rescue the Oracle from Robotnik.|
|31||"Country Crisis"||How You Play the Game||Laren Bright||21 April 1999||11 October 1999|
|The Sonic Underground are on a mission to stop a group of hillbillies from feuding so they can stop Robotnik's building project from flooding the countryside.|
|32||"Haircraft in Space"||Don't Be a Backstabber||Tracy Berna||25 April 1999||12 October 1999|
|A salon robot is hypnotizing people that go to her salon into revealing deep secrets. When Sonia goes she reveals the location of their new base.|
|33||"Healer"||We're the Sonic Underground||Ben Hurst and Pat Allee||28 April 1999||13 October 1999|
|A Mobian named Titus creates a machine that can de-robotisize robots called the De-Roboticizer.|
|34||"Sonia's Choice"||Never Easy||Ben Hurst and Pat Allee||2 May 1999||14 October 1999|
|Robotnik is about to auction four royal goblets in Anèz. When the hedgehogs take the goblets back Sonic and Manic are captured. At both ends of the city are Roboticizers with one of Sonia's brothers inside.|
|35||"The Big Melt"||Fun in the Sun||Len Janson||5 May 1999||15 October 1999|
|What started as a vacation for Sonic, Sonia and Manic gets ruined by Dr. Robotnik when he comes up with a plan – to melt the polar ice caps. Sonia gets split up from the group and mistaken for Queen Sauna by a group of penguins who are having troubles of their own.|
|36||"Sleepers"||Have It All Again||Ben Hurst and Pat Allee||9 May 1999||18 October 1999|
|Robotnik invents a new dart that induces sleep and sends them after the resistance. The hedgehogs attempt to stop them from the source. Manic is hit by the sleeper darts. After destroying the sleepers, they attempt to destroy the fuel source in the Bad Lands' Mine.|
|37||"Bartleby the Prisoner"||Justice Calling||Elenor Burian-Mohr and Terence Taylor||12 May 1999||19 October 1999|
|Bartleby is placed under arrest for helping out the resistance.|
|38||"The ART of Destruction"||The Sound of Freedom||Laren Bright||16 May 1999||20 October 1999|
|The Sonic Underground come across ARTT (Artificial Robot Thought Technology), Robotnik's new robot, that can think and learn for itself. ARTT soon learns the power of friendship and switches to the Resistance. This gives Sleet the opportunity to finish off ARTT and the hedgehogs before time runs out.|
|39||"The Pendant"||Lady Liberty||Ben Hurst and Pat Allee||19 May 1999||21 October 1999|
|While combating Sleet and Dingo in the newly discovered Emerald Peninsula Sonia finds a magic pendant that threatens to turn her invisible. Sonic and Manic race against time to find the cure to this seemingly irreversible spell before Sonia disappears forever.|
|40||"Virtual Danger"||Don't Let Your Guard Down||Ben Hurst and Pat Allee||23 May 1999||22 October 1999|
|Sonic and Manic get addicted to a new video game that is hindering Cyrus' plan to infiltrate Robotnik's base. Sonic and Manic soon find out Robotnik is behind everything and is ready to eliminate them.|
It is often claimed that SEGA contacted DiC Entertainment to make a new Sonic cartoon, which would help gain interest in buying their new console, the Dreamcast. Sonic Underground started production in early 1997, around the same time the development of both the Dreamcast and Sonic Adventure had started. The show bible was written as early as March 1997. The show was publicly announced as early as December 1997.
When the show was in development, two episodes per week were produced, and the writers felt that they were not given enough time to "tie everything together" in the plot, being limited to a three-part "Origins" saga for coherency. DiC used cattle calls to generate episode plots. Periodically, about twenty unaffiliated writers were brought into the studios to learn about the established characters and brainstorm possible plots for episodes, after which about one or two would be selected.
While it was once believed that 65 episodes were made of which only 40 aired, Ben Hurst, a main writer from Sonic the Hedgehog (dubbed SatAM by fans), who was also involved in Sonic Underground's production, stated in a chat at the Sonic Amateur Games Expo 2008 that only 40 were produced.
Sonic Underground first premiered in France on 6 January 1999 and aired on TF1 on the TF! Jeunesse block on Wednesdays and Sundays.  The show later premiered in English in the UK on 2 May 1999 and aired on ITV1 on Sunday mornings. ITV1 aired the first 18 episodes in the original UK run before cancelling the show.
In the United States, Sonic Underground premiered on 30 August 1999 (one day after the show was cancelled in the UK) and aired on the Bohbot Kids Network syndication block on weekday mornings at 6:00 AM Central Time. It ran for one season from 30 August 1999 to 22 October 1999. On the Sci-Fi Channel (formally part of the Bohbot Kids Network), the episodes that were supposed to air on Fridays were skipped because Double Dragon and later King Arthur and the Knights of Justice were airing instead, therefore only airing 32 of the 40 Sonic Underground episodes. It also aired in Canada on Teletoon.
Sonic Underground was later rerun. In the United Kingdom in 2005, Sonic Underground aired on Pop, which has also aired Adventures of Sonic the Hedgehog on its sister station Kix!. Between 2005 and 2006, it aired on ITV2 on the Action Stations! block. On 19 January 2006, CBS announced a multi-year deal with DIC to broadcast some of their shows on the "CBS's Secret Saturday Morning Slumber Party" segment, including Sonic Underground. In 2009, reruns of Sonic Underground aired on Firestone Communications' Sorpresa, a Hispanic children's station (Channel 850 on Time Warner Cable) in the United States, were broadcast audio-dubbed Latin Spanish episodes. In 2011, the show was broadcast by KidsCo. Re-runs of the series aired on Disney XD starting 11 June 2012 and ending on 14 December 2012. This makes it the second time a Sonic the Hedgehog cartoon airs on a Disney-themed channel with the first being Adventures of Sonic the Hedgehog on Toon Disney.
The complete Sonic Underground series, comprising all 40 episodes on 10 DVDs, was released by Anchor Bay in the UK, compatible only with region 2 players. The entire series was re-released by Delta, who released a 4 disc DVD set with a 5th DVD containing bonus features for region 0 players. In return the entire series was re-released by GO Entertain, in the UK, compatible only with region 2 players.
Shout! Factory and Vivendi Entertainment have released the complete series on DVD in Region 1 (NTSC) in two volume sets. Volume 1, simply entitled Sonic Underground, was released on 18 December 2007. It contains the first 20 episodes of the show on three discs; a bonus fourth disc is an audio CD containing eight songs from the series, including the opening theme. Sonic Underground: Volume 2 was released on 17 June 2008, featuring the remaining 20 episodes. In May 2013 NCircle Entertainment released Volume 1 along with many of the older SEGA and Nintendo cartoons that were already released by Shout Factory. Most of the newer NCircle's releases are copies of the Shout Factory versions.
Sonic Underground received mixed reviews: it was criticized for its complex plot and large amount of differences from the games, although some critics have defined the music as catchy. David Cornelius of DVD Talk said "While many Sonic fans did not take too well to all the changes, preferring the original "Sonic" cartoon to this stranger, sometimes darker, sometimes sillier incarnation, the series did win a small but loyal cult following. I fall more on the side of disappointment - for all the cleverness that went into crafting an all-new backstory, the episodes themselves are uninspired - but acknowledge the simple fact that it scores well with its target audience." GamesRadar called the show as one of "the absolute worst Sonic moments", criticizing the extra characters and the complex plot. Patrick Lee of The A.V. Club panned the series, calling it one of the most artistic failures to ever end up on television and "the result of several unrelated ideas forcibly squashed into one project". Comedian Chris Hardwick commented on the show's theme song, composed by Mike Piccirillo, claiming that "that guy sounds like he's trying to win his exwife back." Susan Arendt of Wired said "The songs are actually kind of catchy in a Saturday morning cartoon kind of way, but the band thing still seems a bit out of place, especially when the instruments turn into weapons." Emily Ashby of Common Sense Media said "Sonic Underground has some good things to offer kids, but only if they're ready for the complexities of its story" criticizing its complex plot but complimenting its low violence and ability to entertain children. Mick Joest of Cinemablend called Sonic Underground one of the "5 Best Cartoon Bands Of All Time."
The Sonic the Hedgehog comic from Archie Comics featured a story in one of its special issues in which the Sonic Underground continuity was featured. According to the comics' plot, the reality in which Sonic Underground takes place is one of many parallel universes that share elements with Sonic's own. In the story, Sonic Prime-hailing from the main universe in the comic series-joins forces with his counterpart and siblings to stop Dr. Robotnik, who has managed to assemble a monstrous battle machine known as the Giant Borg. Robotnik obtained the pieces for this machine due to being mistaken for one of his own counterparts by Evil Sonic, an evil counterpart of Sonic's who later came to be known as Scourge the Hedgehog.
The Sonic Universe spin-off comic was originally scheduled to feature an epilogue to the unfinished Sonic Underground for its 50th issue. However, for unknown reasons this was replaced with a story focusing on one of Sonic's long-running enemies, Metal Sonic. The Underground Epilogue has apparently been put on hold indefinitely, possibly due to its lack of relevance to current Sonic games and the comic series as a whole.
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