- "Sonic's world" redirects here. For other uses of the term, see Earth (disambiguation) and Sonic's world (disambiguation).
The earth (地 chi?), also referred to as Sonic's world, is the overall main setting of the Sonic the Hedgehog series. It is a lush and beautiful planet inhabited by various creatures, most notably humans and anthropomorphic animals. The planet is notable for its many oddities, and over the course of its history, many crises have arisen on it, several of which have threatened the existence of the planet and reality as a whole.
In the present day, Dr. Eggman, a human super-genius, seeks to conquer the earth and enslave its inhabitants. At every turn however, the doctor's plans for world domination have been thwarted by Sonic the Hedgehog and his numerous friends and allies.
Concept and creation
Sonic the Hedgehog was created as a mascot for Sega, replacing its former mascot Alex Kidd. In order to maximize the appeal of the new character, his background (and the planet on which he lived) was given no detailed information in any of the initial games of the series (from the first game through to Sonic R). This allowed the separate branches of the company (Sega of Japan, Sega of America and Sega of Europe) to each create its own stories to fit third-party sponsors such as comics and animated television series.
Sonic's planet was named Mobius by Sega of America in their 1991 series bible. This was adopted into the western cartoons and comics, and occasionally mentioned in the video game instruction manuals. However, since the release of Sonic Adventure, this name was no longer used in association with the video games.
The planet was originally unnamed except in other media, in which most early continuities instead took place on the fictional planet Mobius. With few exceptions, the planet's name in the games was never mentioned; however, games were generally assumed to take place on a fictional earth, with some locations based on real-world places. In keeping with the original Japanese script, it was called “earth” in Sonic Adventure 2, marking the first use of the name in a game's English localization. Since then, it has been reused in many scripts.
The earth, much like the real-life planet, is a spherical astronomical body. It possesses a breathable atmosphere that burns up small Solar System bodies on a collision course with the planet, and its surface is covered mostly in water, making it primarily blue in color. However, dotting the earth's surface are also a number of massive continents that can be seen from orbit, as well as a "bajillion" of smaller islands that cannot be seen from space. In addition, the earth possesses two moons. The most prominent of these is the moon, a satellite that orbits earth and illuminates the planet during nighttime. Other satellites and similar objects include Little Planet, a tiny world that appears above a certain place on earth for one month every year and vanishes completely for the remaining eleven months, and the Lost Hex, an unexplored floating continent hidden in the earth's sky.
The landscapes covering the earth are very diverse and abstract at times, to the point that the entire planet can be considered a pretty crazy place, namely due to its checker-patterned soils, floating islands of various sizes, and natural loop-de-loop rock formations, which can be attributed to the "twisty, bouncy beauty of nature". Notably, earth's natural environments range from barren deserts and deep canyons to fertile valleys, sandy coastlines, fiery wastelands, frozen polarcaps, grassy hills, expansive jungles and forests, underground tunnel networks, and undersea regions. In addition, the earth has a number of settlements built by civilizations, including ancient ruins, modern metropolises, abandoned fortifications, aerial structures, and humble villages. The earth also appears to be highly advanced in term of technology, as some of the planet's cities seem to be very advanced and futuristic. Robots and breakthrough technology are also common. Cutting-edge cities like Grand Metropolis, Metal City and Monopole in particular hold robots, flying cars, Extreme Gear and transport tubes.
The earth is home to a plethora of different species and creatures coexisting peacefully with one another, including humans, Animals of various species and races, anthropomorphic animals, Chao, and later Wisps; although humans remain the planet's dominant species. The earth also houses several forms of supernatural creatures like ghosts and, for a time, Dark Gaia's Minions; several deities that include Chaos and Solaris; and physical embodiments of nature; such as Dark Gaia and Light Gaia. Even the earth itself has been speculated to have a will of its own.
The earth is full of fascinating countries, each with its own cultures and people. Notably, the planet's anthropomorphic animals usually live on the islands dotting the planet while humans tend to live in the bigger countries. Notable countries on earth include the United Federation, the Eggman Empire, and the Principality of Soleanna. Other countries also exists, each modeled after real-world locations.
Over the course of the Sonic the Hedgehog series, the earth has been portrayed inconsistently, its landmasses and locations having often varied in size and shapes from game to game. Some times, the earth has included locations and areas from the real world, like Japan and South America, and in other cases, it is portrayed with entirely new and original locations not seen elsewhere.
The earth came into existence in the beginning of time. Around that time, two embodiments of the planet's desire for a balance between light and darkness supposedly came into being: Dark Gaia and Light Gaia. From then, on, following an eternal cycle, Dark Gaia would awaken once every couple of millions of years from the earth's core after gathering enough strength, breaking the planet apart in an attempt to destroy it until Light Gaia stops Dark Gaia and restores the damage done during an event known as the time of awakening. Once this event has passed, these two entities would return to sleep in the earth's core until they are able to awake to continue their cycle. Ages ago, to help restore the planet whenever it got broken apart, the Gaia Temples were built around the world to house the planet's power.
Throughout history, the legendary and powerful Chaos Emeralds have played an integral part of the history of earth, though no one knows where they come from. Notably, in the distant past, the people of West Side Island used these Emeralds to develop their civilization and achieve great prosperity. However, this prosperity was lost overnight when these people tried misusing the Chaos Emeralds, supposedly prompting the gods to seal them somewhere on the island. Existing as a counter to the Chaos Emeralds however, is the Master Emerald, another relic of unknown origin with the special power to neutralize the Chaos Emeralds' energies.
Over the course of earth's history, many historical events have occurred, most of whose placements in history are unknown. Notably, in the far past, a group of aliens known as the Babylonians crash-landed on earth when they were forced to eject their engine units, the Arks of the Cosmos, from their spaceship, which would become known as Babylon Garden, into the orbit around earth in order to prevent the formation of a black hole. Making a life for themselves on earth, they made Babylon Garden their home, which became known as the "divine wings" (神の翼 Kami no tsubasa?), a legendary bird that the gods rode through the heavens. However, the Babylonians, still longing to go home, would also wait for the Arks of the Cosmos to fall out of orbit so they could use them to go home. In time, the Babylonians recovered two Arks of the Cosmos and put them in secure locations. Over time, the Babylonians also became a legendary band of great thieves and Extreme Gear specialists known as the Babylon Rogues, who would roam the world looking for treasure. However, accordingly, the Babylon Rogues ended up incurring the wrath of the Gods, who cast Babylon Garden into the depths of the earth, leaving the Babylonians scattered for all time. However, a branch of the Babylonians, known as the Babylon clan, would endure and continue their thieving ways as the Babylon Rogues for generations to come, passing down the Key to Babylon Garden along with them.
4,000 years ago, there was a culture known as the Fourth Great Civilization. This civilization created a weapon known back then as the "Gizoid", a learning robot capable of copying combat and weapon data, as well as harnessing the Chaos Emeralds' power. Eventually though, the Gizoid's great power caused the destruction of the Fourth Great Civilization, and the Gizoid itself vanished.
Approximately 3,000 years ago, the Chaos Emeralds and the Master Emerald resided in the Altar of Emerald. This altar and the Chao inhabiting it were guarded by a deity known as the Sprit of Water. Back then, there was also an ancient civilization of echidnas known as the Knuckles Clan, which ruled the territory encompassing the Mystic Ruins during a time or rivaling warlords. During his leadership of the clan, Chief Pachacamac, seeking domination and power, led his clan into a series of successful wars that greatly increased the Knuckles Clan's prosperity. Unsatisfied however and hungry for more power, Pachacamac plotted to steal the Chaos Emeralds. Disapproving of his warmongering, Pachacamac's daughter, Tikal, tried preventing this unnecessary raid. However, her efforts were for nothing, and Pachacamac ultimately injured both Tikal and many Chao when he attacked the altar. Seeing its friends hurt, the Spirit of Water became a corrupt being through anger and sadness, and used the Chaos Emeralds to turn into Perfect Chaos. As Perfect Chaos attacked the Knuckles Clan though, Tikal sacrificed herself to seal herself and the Spirit of Water inside the Master Emerald before Perfect Chaos could destroy the rest of the world. After that, the Chaos Emeralds were lost and the Spirit of Water became known as "Chaos". Humbled by the attack, the remaining members of the Knuckles Clan used the Master Emerald's power to suspend the Emeralds' altar area into the sky, creating Angel Island. There, the Knuckles Clan would live, bearing the duty of observing and protecting the Master Emerald, so that an incident with Chaos would never happen again. Over the years however, the Knuckles Clan entered terminal decline.
Another alien race, known as the Black Arms, would also observe the earth. These beings inhabited a celestial object known as the Black Comet that passed by the earth every fiftieth year. Their leader, Black Doom, in particular planned to harvest the earth's human population as food for his heirs as a part of his prosperity ritual. However, the earth's atmosphere prevented Black Doom from bringing the Black Comet down to earth for his ritual. Over 2,000 years ago, to aid with his plans, Black Doom had an armada of sky ships transported down to earth in Glyphic Canyon.
Over fifty years ago, Professor Gerald Robotnik, one of the most brilliant minds in earth's history, was approached by the President of the United Federation of that time to create the Ultimate Life Form, which the government planned to use as a weapon for war. Though Gerald refused to do so at first, he found out that he could find a cure for his granddaughter, Maria, who suffered from the incurable Neuro-Immune Deficiency Syndrome decease by co-opting the immortality research. Starting work on "Project Shadow" onboard the Space Colony ARK, a research station in orbit around the earth, Gerald and his fellow researchers went to work. During the development however, Gerald needed help, and so contacted Black Doom when the Black Comet made its pass by earth. The two of them then made a deal: Black Doom would provide Gerald with a sample of his DNA for Project Shadow, and Gerald would have his creation bring Black Doom the seven Chaos Emeralds the next time the Black Comet returned in fifty years. However, Gerald eventually discovered Black Doom's real plans and so developed the Eclipse Cannon to destroying the Black Comet and the Black Arms with it upon their return. Eventually, with the aid of Black Doom's DNA, Gerald created the ultimate life form: Shadow the Hedgehog. During this time, Gerald also found the Gizoid and discovered its capabilities, prompting him to research for a way to keep it under control and keep it from being used for evil. Despite this, with the upper echelon going crazy and threatening to freeze Project Shadow, Gerald handed the Gizoid over the government as a bribe to buy more time for his research. Unfortunately, the Gizoid soon went out of control before being subdued. Unable to destroy the Gizoid, Gerald resorted to programing it with a free will so that it could choose not to become a weapon of mass destruction. Eventually though, GUN came to regard Gerald's research as too dangerous. As such, GUN enacted an operation where they invaded the ARK and began exterminating everyone related to Project Shadow, with the goal of detaining Gerald and contributing the subsequent shutdown of the ARK to an accident. During the attack, Maria was killed while sending Shadow down to earth. Afterwards, Gerald was detain and brought to Prison Island to continue his work on Shadow, who had been found by GUN and put into stasis on Prison Island, under military control. Unable to cope with the loss of Maria, Gerald slowly went insane. After putting the finishing touches on the Gizoid's free will program, Gerald finally lost it and sent up a plan that would destroy the earth as his revenge on humanity for Maria's death, which he brainwashed Shadow into enacting when he awoke. Not long after, Gerald was executed when GUN began fearing his retaliation.
Ten years ago, the Duke of Soleanna began the Solaris Project in hopes of harnessing the time-controlling powers of Soleanna's deity, Solaris. However, the project backfired, resulting in Solaris being split into Iblis and Mephiles the Dark. With the aid of Shadow and Silver however, who had come from the future to witness the Solaris Project, Mephiles was sealed inside the Scepter of Darkness while Iblis was sealed inside the Duke's daughter, Princess Elise, although the Duke died soon after.
In the recent past, Gerald's grandson, Dr. Ivo Robotnik, began planning to establish his own empire and dominate the world. Some of his earliest operations involved establishing MeteorTech, a security company which he secretly used to plant his robot armies everywhere; and building a massive interstellar amusement park to harness the Hyper-go-on energy of the alien Wisps. However, he was unable to finish the park until years later. In addition, his other plans for domination would be wrecked by a young hedgehog named Sonic, who eventually became Robotnik's worst enemy.
In other media
Sonic the Hedgehog: The Movie
In Sonic the Hedgehog: The Movie, the earth goes mainly by the name of Planet Freedom, and serves as the home planet of Sonic and his friends and enemies. In this media, it is divided into two layers: the Land of the Sky and the Land of Darkness.
In Sonic X, it is revealed that Sonic, his friends and Dr. Eggman originate from an alternate reality version of Earth. A long time ago, Sonic's world and Earth were once one, but a cataclysmic event split the planet into two and sent them to different dimensions. The flow of time in Sonic's world is considerably slower than on Earth, with one month in Sonic's world equaling an entire year on Earth.
When Sonic came to Earth, the two worlds began to merge into one once again, which would ultimately stop the flow of time completely, thus forcing Sonic and co. to return to their world.
In the Sonic Boom franchise, earth is where the series takes place. In this media, the planet resides in the Sonic Boom World and holds a mysterious past that has spawned both legends and lore alike. Its surface consists mostly of lush and wild nature filled with jungles, mountains, undersea civilizations, cloud cities, and all kinds of other environments. The earth has very little urbanization and most of the residents live in and around a Village. The series centers around Seaside Island where Team Sonic fight against Dr. Eggman to keep the doctor from achieving domination over the planet.
The majority of the planet's population is made up of anthropomorphic animals referred to as animal people, though humans like Dr. Eggman are also present. While civilization here is predominantly rustic, modern commodities such as ice cream stands, airplanes, televisions and highly advanced technology are also found here, though in much lesser quantity. A few places on the planet, like Dr. Eggman's lair and the Ancients' civilization, are highly futuristic and technological areas.
Books and comics
Sonic the Hedgehog (manga)
In the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics, the Earth was almost identical to the real-world planet, with a history virtually identical to its real-life counterpart. In the early 21st century, however, Earth was contacted by an alien race known as the Xorda. However, the Xorda ambassador was captured and dissected by humanity, and the aggressive Xorda race declared war on Earth. Though some of humanity managed to preserve themselves, the Xorda ended the world with their Gene Bombs which broke all forms of life down to their basic components. Thousands of years later, this combined biomatter gave birth to the mobian race, who would repopulate the earth and rename it Mobius.
After the Super Genesis Wave re-wrote history, Mobius became known as Sonic's World. The planet is now virtually identical to its game counterpart.
Sonic the Comic
Earth appeared in the British series Sonic the Comic, but in this continuity it is considered entirely separate from Sonic's home planet of Mobius. In an early Sonic's World strip, the Kintobor Computer claimed that Mobius was in a small galaxy that was "117,63222[sic] light years from Earth", in a parallel dimension, in a different time zone and the whole region is made up of dark matter.
Amy Rose and Tekno the Canary crash-landed on Earth in a space ship after being teleported across the universe accidentally. During this short stay, they were mistaken for aliens. They befriended a human named Professor Cratermass and earned the enmity of Colonel Granite, the deranged commander of Operation Starwatch, who believed they were the vanguard of an invasion fleet. Amy and Tekno managed to escape and teleport back to Mobius with some help from Professor Cratermass, who deleted the teleportation program afterwards so that Colonel Granite couldn't follow. Amy and Tekno encountered Granite again on Earth during their trips through the Ring of Eternity, and as a result of this story, rogue British military forces led by Colonel Granite subsequently invaded Mobius before being hurled out by the spirit of the planet itself. An even later story showed that, due to their highly similar ecosystems, Earth and Mobius were twin planets.
In the Sonic the Hedgehog film series produced by Paramount Pictures, Earth is a planet on the far side of the universe. Sonic was sent to Earth to hide from people who want to use his power by Longclaw. In this media, the Earth closely resembles the real planet.
After staying in hiding on Earth for ten years, Sonic accidentally made his presence known to the United States government, who sent Dr. Robotnik out to investigate the matter, prompting Sonic to try and leave Earth. Robotnik himself tried to capture Sonic, but with the aid of Tom Wachowski, Sonic banished him to the Mushroom Planet. Afterward, Sonic settled down on Earth once more, but in the company of the Wachowski family.
- Sonic Chronicles: The Dark Brotherhood is the first and only instance in the series so far to use the terms "earth", "Sonic's world", and "Sonic's World" in the same game.
- In interviews, Takashi Iizuka said that the Sonic games takes place across two worlds: one is human, and the other one is set on the non-human side, the latter which Sonic Colors takes place in. However, has not been clarified if whether this means the games literally take place across two different versions of the earth (like in Sonic X) or across different societies. The PR and Social Media Manager of Sonic the Hedgehog Aaron Webber (to his understanding) confirms the former while former Sega Europe community manager Kevin Eva disapproves the former. In a later interview, Iizuka stated that the portrayal and nature of the earth depends on which of these two worlds is being portrayed in each game, and sometimes there may be some "crossovers" between them.
- Ian Flynn also backed up the former idea, stating that according to Sega, Sonic's world and the human world are two separate planets, with travel between them accomplished via the use of Giant Rings. However, Flynn later implied that this was no longer officially considered to be the case, though stated that he was unable to elaborate.
- As of the first official broadcast of TailsTube, this bit of lore appears to no longer be considered to be part of the Sonic series, as humans and anthropomorphic animals are referenced to as both inhabiting a single world.
- Sonic Team (23 June 2001). Sonic Adventure 2. Dreamcast. Sega. "Maria: Shadow, what do you think it's like on earth?"
- Sonic Team (12 November 2010). Sonic Colors (Wii). Sega. "Dr. Eggman: Soon the mind control weapon will be full of energy I've siphoned from the aliens, and Sonic's world will be the center of my interplanetary theme park."
- Dimps (21 April 2012). Sonic the Hedgehog 4: Episode II. PC. Sega. "How to Play/Episode II Story: Months after the events of Episode I, the Little Planet of Sonic the Hedgehog CD fame once more nears Sonic's world."
- TailsTube #1 (feat. Sonic). YouTube. Sonic the Hedgehog (24 March 2022). Retrieved on 24 March 2022.
- Sonic Team (November 18, 2005). Shadow the Hedgehog. PlayStation 2. Sega. Area/Level: The Last Way. "Sonic: Those black creatures just warped the comet down to the surface using Chaos Control! / Rouge: No! That's impossible! / Shadow: That's why you needed the Chaos Emeralds. / Black Doom: Hahahaha... precisely. The comet's velocity isn't powerful enough to pass through another planet's atmosphere. The Emeralds amplify the space-time control powers of Chaos Control. We need them to charge to full power. It's the perfect plan. That's why I needed the professor to help me..."
- Dimps, Sonic Team (7 June 2004). Sonic Advance 3. Game Boy Advance. Sega. Area/level: Chaos Angel.
- Sonic Team, CRI Middleware (22 February 2008). Sonic Riders: Zero Gravity. PlayStation 2. Sega. Area/level: Crimson Crater.
- Sonic the Hedgehog CD (2011) instruction menu, "A World That Defies Time"
- Sonic the Hedgehog CD (Sega CD) Japanese instruction booklet, pg. 4.
- Berry, Jason (12 June 2013). TSS @ E3: TAKASHI IIZUKA INTERVIEW “PURE PLATFORMING ACTION”. The Sonic Stadium. Archived from the original on 15 June 2013. Retrieved on 27 March 2022.
- Sonic Team (25 February 2015). Sonic Runners. iOS. Sega. Area/level: Episode 6. "Tails: He said everyone else followed Mama Wisp back to their home planet... but that he liked it here, so he stayed behind! / ... / Tails: No, he says there are others who stayed behind, too. He says they all remember who you are Sonic, and he's sure they'd be happy to help you!"
- Sega. ソニック ＆ ウィスプ キャラクター紹介 (Japanese). ソニック ＆ ウィスプ キャラクター紹介. Sonic Channel. Archived from the original on 10 September 2021. Retrieved on 12 September 2021.
- Sonic Team (9 December 2008). Sonic Unleashed. PlayStation 3. Sega. Cutscene: Save the Speech. "Prof. Pickle: We cannot live without the night. We all must sleep. We all must rest. Darkness is a part of our world, just the same as light. It may be that the darkness has not been destroyed, but merely laid to rest. It grows strong over the eons, rises up, then is put to slumber by the light. Perhaps that is the true balance of Dark and Light Gaia. That balance may be the very will of the planet itself."
- Sonic Team (9 December 2008). Sonic Unleashed. PlayStation 3. Sega. Cutscene: No Reason. "Chip: My... My real name is Light Gaia. I draw power from the day and light, and guide the planet to its rebirth. My job was to protect the planet from Dark Gaia. But Eggman broke the world apart himself, and Dark Gaia and I were awakened before we should've been. That's why Dark Gaia broke apart, and I didn't know who I was. I didn't remember what I was supposed to do. All because this isn't the proper time of awakening. / Sonic: Time of awakening? / Chip: Dark Gaia grows over millions of years, then rises to destroy the world. And I put it all back together. We've been doing this over and over, again and again... since the very beginning of time."
- Sonic Team (9 December 2008). Sonic Unleashed. PlayStation 3. Sega. Area/Level: Professor's Room. "Prof. Pickle: According to the Gaia Manuscripts, there are 7 temples in all. They were built around the world ages ago to house the planet's power."
- Sonic the Hedgehog 2 (Sega Mega Drive) Japanese instruction booklet, pgs. 4-8.
- Sonic Team (3 May 2002). Sonic Adventure 2: Battle. Nintendo GameCube. Sega. Area/Level: Wild Canyon. "Knuckles: The Master Emerald contains special powers that neutralize the energy of the Chaos Emeralds."
- Sonic Team (19 October 1999). Sonic Adventure. Dreamcast. Sega. Area/Level: Mystic Ruins (Big's version). "Tikal: So these are the 7 Emeralds... ?! Could it be? The servers are... the 7 Chaos Emeralds... Unified by one that is the controller... The 7 Chaos... The controller itself... Could this be the Emerald that controls the 7 Chaos?"
- Sonic Team, CRI Middleware (22 February 2008). Sonic Riders: Zero Gravity. PlayStation 2. Sega. "Wave: ...We’ve reached our decision. We must sever the engine unit from this vessel. For if we delay, the contraction of the engine core will lead the lightless black to consume everything."
- Sonic Team, CRI Middleware (22 February 2008). Sonic Riders: Zero Gravity. PlayStation 2. Sega. Area/level: Ending sequence (Babylon Story). "Tails: They crash landed on this planet in ancient past... They disconnected the units... / Amy: And left it in orbit hoping that some day it would fall back down to the surface. Every time they saw a shooting star... / Sonic: I bet they’d wished they could get back to their home planet."
- Sonic Team, CRI Middleware (22 February 2008). Sonic Riders: Zero Gravity. PlayStation 2. Sega. Area/Level: Gigan Rocks. "Amy: Divine wings? / Tails: Yes, the legendary bird that the gods rode through the heavens."
- Sonic Team, Sonic Team USA (17 March 2006). Sonic Riders. PlayStation 2. Sega. Area/Level: Splash Canyon. "Tails: Yes; the mark of the Babylon Rogues. A long time ago, there was a floating island known as Babylon Garden. Supposedly, robbers lived there. According to rumors... this "legendary" band, the Babylon Rogues, were great thieves. Legend also says that the Babylon Rogues incurred the wrath of the Gods because of their crimes, and that the island was cast into the depths of the Earth. After that, supposedly the Babylonians were then scattered for all time, never to be found. But they say that the Babylon Rogue's treasure still remains on that island, waiting to be discovered. There are also rumors that the Babylon Rogues were Extreme Gear specialists."
- Sonic Team, CRI Middleware (22 February 2008). Sonic Riders: Zero Gravity. PlayStation 2. Sega. Area/Level: Gigan Rocks. "Knuckles: ...We, the children of Babylon, seal one star here, and another within the great scar, formed in heaven’s fall, until the time of the divine's wings rising."
- Sonic Team, CRI Middleware (22 February 2008). Sonic Riders: Zero Gravity. PlayStation 2. Sega. Area/Level: MeteorTech Premises. "Jet: They aren't just some rocks. They're spoken of in Babylon clan legend as..."
- Sonic Team (9 December 2008). Sonic Unleashed. PlayStation 3. Sega. Cutscene: Gaia Manuscripts. "Prof. Pickle: These ancient documents are known as the Gaia Manuscripts. They tell the legend of a disaster that befell our planet some tens of thousands of years ago. / Tails: A disaster...? / Prof. Pickle: Quite. And according to the Gaia Manuscripts... this isn't the first time the planet has been broken apart into pieces."
- Sonic Team (27 February 2004). Sonic Battle. Game Boy Advance. Sega. Area/Level: Gimme Shelter (Shadow's Episode). "Rouge: You'll never change, will you? That robot... Gizoid is known as the "Ultimate life form." Just like you, except he's 4000 years older. I heard the Doctor was hiding something really big, and I guess this is it..."
- Sonic Team (27 February 2004). Sonic Battle. Game Boy Advance. Sega. Area/Level: Ending sequence (Sonic's Episode). "Prof. Gerald's Journal 1: I have uncovered a most interesting specimen from the warehouse. I believe it to be some sort of puppet or robot made by an ancient people. At first, I didn't think anything of it, but when I was experimenting on "Chaos Emeralds," it began to move. This suggests the possibility that even the ancient civilizations could harness the power of the "Chaos Emeralds." When I was researching various papers related to the "Chaos Emeralds" and this robot, I discovered that there was a possibility that this robot was something incredible. I don't want to get ahead of myself, but this robot may be the cause of the destruction of the Fourth Great Civilization. I'm not sure I believe it just yet, though."
- Sonic Team (November 18, 2005). Shadow the Hedgehog. PlayStation 2. Sega. Area/Level: Final Haunt. "Shadow: What is that? / Sonic: Once every 50 years, that Black Comet passes by this planet."
- Sonic Team (November 18, 2005). Shadow the Hedgehog. PlayStation 2. Sega. Area/Level: The Last Way. "Black Doom: Hahaha... Ignorant fools. We're here to save the humans from their own demise. We offer... salvation. / Shadow: What? / Black Doom: Their greed, thirst for power and affinity for betrayal has them on a path of self-destruction. Their actions will lead to extinction of their species. We're here to save them from themselves... with our perfect order... allowing them to live through their desperate lives in peace. Humans are a great energy source for us... they will be well kept. / Shadow and others: Whaa?! / Black Doom: Let us begin our ritual of prosperity. Chaos...Control!"
- Sonic Team (November 18, 2005). Shadow the Hedgehog. PlayStation 2. Sega. Area/Level: Sky Troops. "Shadow: I bet no one expected this baby could fly. / Black Doom: I transported this brilliant flying fortress to this planet over 2000 years ago. It's magnificent! The perfect killing machine... ready to impose terror in unimaginable ways."
- Famitsu (10 October 2001). "５０年前の真実". ソニックアドベンチャー2パーフェクトガイド. Enterbrain. ISBN 978-4757706255.
- Sonic Team (27 February 2004). Sonic Battle. Game Boy Advance. Sega. Area/Level: Gimme Shelter. "Rouge: He was not interested in researching weapons. He was researching a way to bring happiness and hope to all people. But, he was forced by the government and by the military to use his research for war. That's why he gave you and Gizoid a "soul." A soul identical to his beloved granddaughter, Maria."
- Sonic Team (18 November 2005). Shadow the Hedgehog. PlayStation 2. Sega. Area/Level: The Last Way. "Gerald: If you're listening to this then the worst has happened... you need to know the truth. The government plans to shut down this research facility. The government plans to cease all of our research... and imprison all who know about you. I made a terrible mistake, Shadow. It's all my fault... making contact with that comet."
- Sonic Team (18 November 2005). Shadow the Hedgehog. PlayStation 2. Sega. Area/Level: The Last Way. "Black Doom: The professor was in development of the ultimate life force but he needed my help. So we made a deal... I helped him and he promised to deliver me the SEVEN Chaos Emeralds."
- Sonic Team (18 November 2005). Shadow the Hedgehog. PlayStation 2. Sega. Area/Level: The Last Way. "Gerald: Shadow... it's up to YOU and only YOU can stop them! I developed the Eclipse Cannon... It's the only weapon that can destroy that Black Comet. Shadow, you are the only hope... to save mankind as we know it. The future of this planet depends on... YOU!"
- Sonic Team (18 November 2005). Shadow the Hedgehog. PlayStation 2. Sega. Area/Level: The Last Way. "Black Doom: Such bravado for a little hedgehog! I thought you were different from the rest... but maybe not. We are more alike than you think... the same blood runs through our veins. / Shadow: This can't be... Uugghh... Just... who are YOU? / Black Doom: Don't you know? You were created from my blood..."
- Sonic Team (27 February 2004). Sonic Battle. Game Boy Advance. Sega. Area/Level: Ending sequence (Tails's Episode). "Prof. Gerald's Journal 2: I am no longer able to ignore the possibility that this robot did in fact destroy the Fourth Great Civilization. I have discovered a stone tablet that explains as much. According to the tablet, "When the figure falls from the heavens, and the Stone of the Gods is joined, all that exists will become one again." Though it is difficult to believe, this robot has been watching my movements, and mimicking all that I do. I was amazed by my scans of this being. Surprisingly, reams and reams of data scrolled and caused my most powerful computer to crash. More intriguing was that the data was all about melee combat and weapons of that age. Eventually, if this being is ever restored to its former state, it will put all that data to use, and recreate all the weaponry and combat abilities that it once had… And that's not all. If my guesses are correct, it will also have the ability to absorb modern weaponry as well. What have I done? I have uncovered a horrible weapon…"
- Sonic Team (27 February 2004). Sonic Battle. Game Boy Advance. Sega. Area/Level: Ending sequence (Rouge's Episode). "Prof. Gerald's Journal 3: I now understand why this being was named "Gizoid". In the ancient tongue, it means "everything." According to the stone tablet, if the Gizoid establishes a "Link" with someone, the Gizoid will swear loyalty to that person. Perhaps it still lacks "Chaos Emerald" energy, but it has been saying the word "Link" to me in broken tones. It went on to explain: "Show me your true strength, and I shall obey. I am all things, and all shall belong to me." So, as it suggested, I brought before it my collection of model guns, and fired them all. Then, suddenly, it said, "I shall follow your every command, and never leave your side." And since then, it refuses to listen to anyone but me. While it still is a fearsome weapon of destruction, while it remains under my control, at least it won't be used for evil. However, if someone with evil intention ever forms a "Link" with the Gizoid… I don't even want to think about what will happen. I must research how one can re-establish a "Link" with the Gizoid…"
- Sonic Team (27 February 2004). Sonic Battle. Game Boy Advance. Sega. Area/Level: Ending sequence (Knuckles's Episode). "Prof. Gerald's Journal 4: The upper echelon is going crazy. Perhaps, they aim to freeze Project "Shadow". Soon, the ultimate life form, "Shadow" will be completed… The application to my granddaughter is also imminent. I cannot just let them stop my study at this point. Because I am the only one who can save my granddaughter's life."
- Sonic Team (27 February 2004). Sonic Battle. Game Boy Advance. Sega. Area/Level: Ending sequence (Amy's Episode). "Prof. Gerald's Journal 5: The higher ups are threatening to shut down this research facility. I had no choice but to hand them the Gizoid to buy more time for my research. I tried to be careful and commanded it to never absorb any dangerous technologies. However, I have heard that other researchers have been making the Gizoid absorb weapons. Apparently, the way to cause the Gizoid to form a new "Link" is to show it power that surpasses that of its former master. While this poses immense danger, I cannot risk losing Maria."
- Sonic Team (27 February 2004). Sonic Battle. Game Boy Advance. Sega. Area/Level: Ending sequence (Cream's Episode). "Prof. Gerald's Journal 6: My worst fears have come true. The Gizoid has absorbed enough weaponry and technology that it has started to go out of control. The resulting rampage resulted in the destruction of most of the "Ark." … I have deciphered the rest of the stone tablet. It says, "When the Gizoid had learned all that it could, it became a god of wrath, and all was destroyed." The researchers somehow managed to subdue the Gizoid and sealed it away. Luckily, it only had one "Chaos Emerald" installed. If it were to have all 7 Emeralds installed, it might destroy the whole planet. The Gizoid is too much of a liability. I tried destroying its core, but nothing I did worked. I understand too little of the technology that built him. My best hope is to try and reprogram its AI into a free-willed, emotions-based AI…"
- Sonic Team (27 February 2004). Sonic Battle. Game Boy Advance. Sega. Area/Level: Ending sequence (Shadow's Episode). "Prof. Gerald's Journal 7: I have heard there was an accident at the research facility. … … … Everything… Everything is gone. My own Maria's name was among the list of casualties. My beloved granddaughter… They tell me her parting words were, "Bring hope to humanity." I have decided that the keyword to activate the Gizoid's free-willed emotions-based AI program will be those very words. "Bring hope to humanity." My poor, poor Maria…"
- Prima Development (20 June 2001). "The Beginning". Sonic Adventure 2: Prima's Official Strategy Guide. Prima Games. pp. 2–3. ISBN 978-0761536147.
- Sonic Team (11 February 2002). Sonic Adventure 2: Battle. Nintendo GameCube. Sega. Area/level: Before Cannon's Core. "Rouge/Gerald: I don't quite know what happened or what went wrong. Was it a mistake to create the ultimate life form? I thought it would be something that would benefit mankind. But then the military guards landed on the colony that day. They were sent to destroy the research project that I had been working on. My colleagues at the research facility, my granddaughter, Maria. I hope you are all safe. The colony was completely shut down, probably to keep the prototype from falling into the wrong hands. The ARK was shut down under the premise that there had been an accident. I found Maria's name among those who died when the ARK was shut down. She meant everything to me and I couldn't bear the thought that she died because of my research. I lost everything. I had nothing more to live for…I went insane. All I could think about was to avenge her…somehow, someway. I got scared as I was no longer able to control my thoughts. All I could think about was that I wanted it all to end. Based on my original projections, I was able to complete my project, Shadow. I designed its mind to be perfect, pure. I will leave everything to him. If you wish, release and awaken it, to the world. If you wish to fill the world with destruction…"
- Sonic Team, CRI Middleware (22 February 2008). Sonic Riders: Zero Gravity. PlayStation 2. Sega. Area/level: Crimson Crater (Heroes Story). "Tails: He's probably planning to use the stones' power to issue an order to all the worlds' robots from this tower. Sooner or later, he was planning to set the robots rampaging. / 'Amy: That was probably his reason for forming the MeteoTech in the first place. / Sonic: The Eggman Land project again, huh? He never gives up, does he?"
- Sonic Team, CRI Middleware (22 February 2008). Sonic Riders: Zero Gravity. PlayStation 2. Sega. Area/level: Ending sequence (Heroes Story). "Mother computer: System error detected. All commands canceled. / Dr. Eggman: My Eggman land plans are in ruins, after all these years!"
- Sonic Colours (Nintendo DS) European instruction booklet, pg. 3.
- Sonic the Hedgehog (Sega Mega Drive) Japanese instruction manual, pgs. 7-10.
- Sanzaru Games (21 November 2014). Sonic Boom: Shattered Crystal. Nintendo 3DS. Sega. Area/Level: Shadow Canyons. "Tails: Well, y'know... multitasking. I also balanced my checkbook, invented a car that can circle the earth on half a jar of kosher pickles..."
- Hit new TV Series Sonic Boom Premiered #1 in its time slot with boys 6-14!* Now on Cartoon Network. Retrieved on 20 November 2014.
- Sonic Boom #1
- Freiberger, Sam (22 July 2017). "Return of the Buddy Buddy Temple of Doom". Sonic Boom. Season 2. Episode 89. Boomerang.
- Sonic the Comic #25, "Prologue: Once Upon a Planet..."
- Sonic the Comic #114 and #115, "Earthbound"
- Sonic the Comic #140 and #141, "Out of Time"
- Sonic the Comic #146 and #147, "Earth Attacks"
- Sonic Colours: Interview with Takashi Iizuka. GAME.com. Archived from the original on 17 August 2010. Retrieved on 13 August 2015. "GAME: Could you tell us a bit about the story behind Sonic Colours? It looks more like the old games, which were set on Moebius, than the new-style Sonics set in Station Square... / Takashi Iizuka: We have two different worlds for Sonic games – one is human, and one is set on the non-human side. Sonic Colours is set on the non-human side. The only human in the game is Dr Eggman, who tries to build this huge amusement park which, as you will see on the world map, ties all these planets together with a tractor beam."
- Swingin’ Report Show #80: Interview with Aaron Webber, Sonic the Hedgehog PR & Social Media Manager. YouTube. SEGAbits II (2 July 2015). Retrieved on 13 August 2015.
- Eva, Kevin (17 August 2015). Sega's Secret Sonic Bible that we'll probably never see "TO MARS!". Sonic Stadium Message Board. Retrieved on 20 August 2015.
- Brian Shea (10 June 2017). More Burning Questions About The Sonic The Hedgehog Franchise Answered. GameInformer. Retrieved on 10 June 2017.
- BumbleKast Q&A for August 10, 2020. YouTube. BumbleKing Videos (10 August 2020). "I have been instructed at multiple points in my career that it is literally two different planets. I received a series bible ... that specified that they are two different planets in two different dimensions ... and it was explained that yes, it's two different planets that are accessed via secret Giant Rings."
- BumbleKast Q&A for July 26, 2021. YouTube. BumbleKing Videos (26 July 2021). "I'm gonna say it again: forget about 'two worlds'. I can't specify why, just don't worry about it anymore ... you know my position on 'two worlds' and I say this with a calm and satisfied smile: don't worry about it anymore."