Sonic the Hedgehog was made to celebrate the 15th anniversary of the Sonic the Hedgehog franchise. It was developed by the Sonic Team and directed by Shun Nakamura.
The game shares its name with a sizable list of other subjects, including two earlier video games, a manga, a television series and, of course, Sonic the Hedgehog himself. To disambiguate, the game has been called by a number of different aliases, including Sonic 2006, Sonic '06, Sonic: 15th Anniversary, Sonic 360 and Sonic Next-Gen. Xbox Live solves the problem by referring to it in all-caps as SONIC THE HEDGEHOG.
The story of Sonic begins in Soleanna, the City of Water, a city based on Venice, Italy. Many fans have discussed if Sonic lives in Soleanna or is just a traveler passing through, though his vast recognition shows that he may stay for extended periods of time.
Soleanna is ruled by Princess Elise, who is the keeper of a dark secret, the "Flames of Disaster", which involves the Chaos Emeralds. The game opens up while the citizens of Soleanna are celebrating the Festival of the Sun; while lighting the ceremonial torch, Elise apparently suffers a terrifying hallucination of the city in flames with a demonic creature composed of molten magma in the center and, as fireworks go off, multiple missiles hit the ground around her, and Doctor Eggman arrives with a small army of robots, revealing his intentions to kidnap Elise, who is, of course, unwilling to comply. At that moment, Sonic arrives, destroys a small number of Eggman's robots, and escapes with Elise while Eggman orders his robots to fire on him. As Sonic escapes, we see a white-furred hedgehog named Silver, who speaks of finally locating the "Iblis Trigger" [note 1]. While running through the city, a confused Elise asks Sonic why he is helping her, but he replies that he has "no special reason". Soon afterwards, more of Eggman's robots attack them, and Eggman successfully captures Elise in the Egg Mobile while Sonic is distracted fighting them. As Eggman returns to the Egg Carrier, Elise throws Sonic her Chaos Emerald, which he catches and assures her that he will rescue her. Unconcerned, Eggman simply decides to let Sonic hold onto "his" Emerald for the time being, and escapes on board the Egg Carrier as Sonic looks on. [note 2]
The next morning, while attempting to gather information on Eggman's whereabouts, Sonic runs into Tails, who has apparently been helping to clean up the city after Eggman's attack. Tails reveals that he knows that Sonic had attempted to save Elise, and offers to help Sonic out however he can; while he doesn't know what Eggman's up to this time, he knows it isn't good [note 3].
After saving a young girl who ended up trapped on a rooftop, Sonic and Tails make their way to the Dusty Desert, where Eggman has been seen, and landing right in the room where he is keeping Elise, who is quite glad to see them (or at least Sonic). At that moment, Eggman arrives and unleashes his Egg Cerberus robot on them,[note 5] which Sonic defeats. Afterwards, Eggman sends a massive amount of robots after them, and Tails creates a diversion in order to allow Sonic and Elise to escape unnoticed.[note 6]
After escaping the desert and entering the plains, Sonic comes to a stop. Elise thanks Sonic for his help, but then notices a wound on his arm. Despite Sonic's insistence that he's fine, Elise bandages his arm with a handkerchief. Blaming herself for Sonic getting hurt, Elise apologizes, but Sonic merely tells her to smile, stating that her smile is all he needs to keep him going. While walking through the plains, Elise fills Sonic in on the Flames of Disaster, Solaris (the sun god honored by Soleanna), how they had nearly faced the full force of his anger, and how she had lost her father in the incident, and fears what would happen if Eggman makes history repeat itself. Without warning, Sonic grabs Elise's hand and runs through the plains with her. Afterwards, Elise lightens up, and Sonic gives her some useful advice.[note 7]
However, upon their return to the city, Sonic and Elise are attacked by Silver, who claims that Sonic's actions will condemn the world, and they battle.[note 8]
Sonic initially has the upper hand, but Silver catches him off-guard and psychokinetically throws him into a building, incapacitating him. Silver demands to know how someone as weak as Sonic apparently is could destroy the world; Sonic asks what he means, but Silver decides that it doesn't matter, as long as the "Iblis Trigger" is destroyed. However, Eggman capitalizes on Sonic's distraction to kidnap Elise again, and Sonic attempts to run after them, but Silver isn't about to let him run off. Silver knocks him down with his psychokinesis, and is about to deliver the coup de grace when Amy suddenly steps in. Silver somehow knows Amy, and orders her to move, but she isn't about to let him hurt Sonic any more. Sonic takes advantage, and, after thanking Amy, runs off after Eggman [note 9].
After a brief encounter with a group of Soleannan soldiers, who accept Sonic's help despite initial reluctance, Sonic enters the warehouse district of the New City and meets up with Tails and Knuckles, the latter of whom gives him a holographic message that he received from Eggman. Eggman negotiates a deal; if Sonic comes to the White Acropolis and gives Eggman the Chaos Emerald that Elise had given him earlier, then Eggman will let Elise go without a fight. Though Tails and Knuckles are both positive that Eggman is setting up a trap, Sonic decides to go anyway, planning to "thank" Eggman for telling him Elise's whereabouts [note 10].
Sonic, Knuckles, and Tails fight through the White Acropolis and enter the room where Eggman and Elise are. Sonic obediently puts the Chaos Emerald onto a small pedestal, but, unsurprisingly, Eggman goes back on the deal and activates a force field, trapping Team Sonic within. At that moment, Eggman activates his Solaris prototype (the name of which surprises Elise), and Sonic and co. vanish into thin air. The minute they vanish, Eggman assures Elise that Sonic, Tails, and Knuckles are still alive (for now), but have been transported to another time period; however, Eggman does not know where they ended up, as he needs a power that Elise apparently possesses and all seven Chaos Emeralds to fine-tune the machine. Sonic, Tails and Knuckles encounter Shadow and Rouge, who are also trapped in this future. In order to return to the present, they need to create a rift in time and space, which they figure can be created if Sonic and Shadow use their Chaos Control together. While searching for Chaos Emeralds, Sonic, Tails and Knuckles encounter Silver, his friend Blaze, and Mephiles, a dark being who resembles Shadow, tells Silver that Sonic is the one responsible for the future's devastation, and takes them back in time to kill Sonic. Sonic learns from a computer file that Elise was killed when Eggman's battleship exploded two days after she was kidnapped. After retrieving a pair of Chaos Emeralds, Sonic and Shadow create the space-time rift, allowing them to return to the present.
Sonic returns for Elise, but is once again attacked by Silver, also allowing Eggman to kidnap Elise again. Fortunately, Shadow arrives to confront Silver, allowing Sonic to rescue Elise, and he returns her to her castle in Soleanna. Later, Eggman arrives in his battleship and threatens to destroy Soleanna, and Elise willingly surrenders herself to him to protect her people. Eggman explains to Elise that in order for his plan to take over the world to work, he requires the seven Chaos Emeralds and the dormant power of the Flames of Disaster within Elise to awaken Solaris, allowing him to harness the sun god's power over time.
On his way to rescue Elise, Sonic encounters Silver once more who, instead of attacking him, expresses concern for Elise as well. The two hedgehogs team up, but before they reach the battleship, it malfunctions, crashes and explodes, just as Sonic feared. However, Sonic and Silver realize they can use Chaos Control to travel back in time to the previous day, before Eggman's battleship launched. Sonic travels to the past alone and reunites with Elise. Defeating Eggman (who battle's Sonic with the Egg Wyvern) one last time, Sonic escapes the exploding battleship with Elise.
Shadow was created by the renowned Professor Gerald Robotnik to be the Ultimate Life-form. In the events after Shadow the Hedgehog, he appears to have joined GUN. His story opens in the midst of a rescue mission of Rouge the Bat, who was sent to retrieve the "Scepter of Darkness" from Eggman's base, and had not been heard from since. Shadow invades the base and finds Rouge in the midst of accomplishing her mission. They escape to the site that was formerly the castle of Soleanna's kings where they are confronted by Dr. Eggman, who attempts to retrieve his stolen property. Eggman's robots swoop down to attack, and in the heat of the battle, the Scepter of Darkness is completely shattered. With the seal crashed, Mephiles is freed.
Resurrected in the likeness of Shadow through his shade, Mephiles the Dark introduces himself and hints at past history that the two shared. Mephiles, using a time warp, similar to Chaos Control, flings Shadow and Rouge to a future on the brink of collapse. When they arrive, they are first perplexed, but before long, they find some disturbing answers. Along the way, they find an inactive, dusty E-123 Omega, lying in stand-by mode for hundreds of years for an unknown reason. They discover that they are in the distant future, destroyed by the demon Iblis. Shadow and Rouge meet up with Sonic, Tails, and Knuckles, who were sent to the future by Eggman's latest machine. Sonic and Shadow conclude that they must use Chaos Control to get home, and set out to locate the Chaos Emeralds. After a confrontation with Iblis, they succeed in finding two Chaos Emeralds and successfully create a time warp to the present. Sonic and company go back to their time, except for Shadow, who stays to confront Mephiles. Upon catching up with Mephiles, he reveals to Shadow that the humans, looking for someone to blame for the destruction of the Earth, saw Shadow responsible for the catastrophe. Shadow is hunted down, defeated, and trapped behind an energy seal. Mephiles tempts Shadow to join him to gain vengeance upon the humans, but Shadow refuses, at which point Mephiles transforms into his second form, a more powerful crystalline monster, and the two engage in battle.
Rouge, in the present, realizes that Shadow is alone in the future fighting Mephiles, without a Chaos Emerald. She searches for E-123 Omega, gives him a Chaos Emerald, and tells him to sit and wait in stand-by mode until the distant future becomes the present, and to assist Shadow fighting Mephiles. Shadow, at Mephiles' mercy, is rescued by Omega, who gives him the Chaos Emerald and helps Shadow fight Mephiles. Defeated, Mephiles flees to the present through a time warp and Shadow and Omega follow him to the present. Omega pursues Mephiles, and Shadow finds Rouge, who informs him that Dr. Eggman is apparently searching for him. Shadow concludes that Eggman is searching for Mephiles, and goes to interview the doctor. Upon locating Eggman's base, Eggman tells him that, to understand why he wants Mephiles, Shadow must know about the accident that happened 10 years ago, the Solaris Project.
Shadow then leaves only to find Sonic, who is under attack by Silver. Shadow rescues Sonic, who runs away with Princess Elise, and Shadow engages in a fight with Silver. Shadow is able to overcome him by freezing time so Silver cannot defend himself. Refusing to just be defeated, Silver also induces Chaos Control, to Shadow's shock. Shadow tells Silver that in order to understand more about Mephiles and Iblis, they would have to use the warp and witness the accident themselves. So the two of them, using the Emeralds, open a time warp to 10 years ago, the Solaris Project. They witness the Solaris Project's failure at hand, and watch as Iblis and the original Mephiles, a dark puddle, emerge, opening Silver's eyes to Mephiles' deception. Duke Soleanna tells them that the demons must be sealed, so he gives Shadow the Scepter of Darkness. Shadow goes to capture Mephiles, and Silver goes to capture Iblis. It is here that Shadow finds out why Mephiles knows him; it was Shadow who sealed him in the Scepter of Darkness in the first place. With the demons sealed, Shadow leaves the Scepter in the past since he knew where it would end up in the present day. Silver and Shadow return and Shadow rushes off to find Rouge to tell her what he learned about Mephiles. Shadow finds Rouge, and tells her to find out what the Scepter of Darkness, Mephiles' seal, was made of, so they can create another one.
Elsewhere, Omega has found Mephiles on the beach and defeats him once again, but Mephiles laughs and tells Omega that the reason he can defeat him so easily is because he was built to defeat Shadow later on. Omega refuses to acknowledge the truth at first but after Mephiles escapes again he admits to Shadow and Rouge that he was the one that sealed Shadow in the future. Shadow, Omega, and Rouge chase Mephiles to a desert temple with a new Scepter of Darkness, but the evil Mephiles has already found the yellow Chaos Emerald. After Shadow fights him and gains victory, Mephiles reverts back into his original form, a puddle of darkness. Shadow attempts to seal him in the new Scepter of Darkness, but it shatters and Mephiles is able to free himself. Mephiles reveals that what worked ten years ago no longer does because he is using Shadow's form. Mephiles uses his powers to summon a giant clone army of himself and he attempts, once again, to trick Shadow by convincing him that he is a fool for continuing to protect those who will eventually seal him away. In response, Shadow replies, "If the world chooses to become my enemy, I will fight like I always have!" Mirroring a similar ability from Sonic X, Shadow removes his power rings, and, in a huge burst of energy, defeats the Mephiles clones with his allies and the story ends as a cliffhanger.
Silver lives 200+ years in the future where telekinetic powers are a common ability.  In the future, Silver's world is completely destroyed by what is known as the "Flames of Disaster". Fought by Silver and his partner and best friend, Blaze the Cat, this is known as an immortal being known as "Iblis". After Silver becomes frustrated over the fact that Iblis cannot be defeated, a mysterious figure named Mephiles suddenly appears and, along the way, informs Silver of the time when Iblis was first unleashed onto the world. He tells him that Sonic was the main cause of the "Flames of Disaster" and refers to him as the "Iblis Trigger". Mephiles sends himself along with Silver and Blaze back in time to the point when "the Iblis Trigger was alive" to prevent Sonic from destroying the future. Upon reaching the present day, Silver realizes that he got separated from Mephiles and Blaze and, elsewhere, Blaze makes the same realization. When Silver has his sights finally set on the Iblis Trigger, he is interrupted by Amy, who mistakes him for Sonic. Amy quickly develops a friendship with Silver, and she promises to help him find who he is looking for, not realizing that he plans on finding and killing Sonic. After locating Sonic in the city, Silver engages him in combat and just as Sonic is about to be killed by Silver, he is saved by Amy. While Sonic runs off to find Elise, who was kidnapped by Eggman during the battle, Amy gets upset over the fact that Silver would even suggest that Sonic would destroy the world in the future and she quickly leaves Silver. Both confused and puzzled when Blaze finds him, Silver questions whether or not he should kill Sonic just for the sake of saving the future. To find more answers, Silver and Blaze journey to Eggman's base. After resolving that he should kill Sonic, Silver finds Mephiles, who tells him that Sonic is at the terminal station. Silver heads there and fights Sonic again, only to have Shadow save Sonic just as Silver was about to finish him off. Silver mistakes Shadow for Mephiles and Shadow corrects him. The two battle it out and actually induce a Chaos Control using the two Chaos Emeralds they have in their possession to teleport into the past and find out what went wrong. Silver and Shadow arrive at the perfect moment, during the explosion that releases Mephiles and Iblis in the first place and, ultimately, causes Duke Soleanna's death.
Shadow seals the original Mephiles in the Scepter of Darkness and Silver learns that to defeat Iblis, they must seal him inside someone's soul, making that person into a sort of vessel. Silver also learns more of Mephiles' intentions and discerns that he lied to him about Sonic being the Iblis Trigger. Upon returning to the present, he meets up with Blaze, shares his findings and has a change of heart, resolving to help Sonic save Elise. Unfortunately, Sonic, Silver and Blaze arrive too late, as they watch the Egg Carrier explode causing the death of Elise and possibly Eggman as well. Silver then tells Sonic that if they use Chaos Control, Sonic can save Elise. Sonic rushes into the past to save Elise and gives Silver a Chaos Emerald for him to return to the future. After journeying back to the future, resolved to finally defeat Iblis, Silver and Blaze fight Iblis and successfully defeat him. When Silver tries to seal him, though, by using himself as a vessel, Silver is unable to use himself as a vessel to seal Iblis. As the ultimate sacrifice, Blaze uses herself as the vessel, sealing both herself and Iblis into another dimension to save both Silver and her world. Disturbed over the loss of a good friend, Silver becomes upset, unsure if what he had set out to do was worth what he had to pay in the end. Nevertheless, light returns to Silver's world, and the game ends with him glaring at the Chaos Emeralds Blaze sealed herself with.
The Last Story begins with Mephiles sporting an evil look as he finally seems prepared to merge with Iblis and destroy the world. Using his Purple Emerald, Mephiles blinds Sonic and Elise, who were continuing their stroll from where Sonic's storyline left off. When they are distracted, he rises from the ground and launches an energy beam (dubbed the "Dark Chaos Lance") that impales Sonic through the back, killing him instantly. Elise frantically attempts to revive Sonic, but upon discovering that he is indeed dead, cries in despair, releasing Iblis. At this point, Mephiles absorbs Iblis, Mephiles then mutates into a monster known as Solaris and then creates his own world to destroy time itself. Continuing from where Shadow's story ended, he and his friends recover from their battle with the Mephiles clones and Shadow notices the Green and Yellow Chaos Emeralds that Mephiles left behind. These create a blinding flash that send Shadow, Rouge and Omega to the time-space rift formed by Solaris. Meanwhile, in Soleanna, Amy, Tails, and Knuckles notice a large bright light that engulfs the city. When the light fades, they realize that they have also been transported to the rift where all of the previous levels in the game exist. Amy is the first to spot Silver, who has been teleported here as well by the Chaos Emeralds that Blaze used to seal Iblis within her. Everyone notices that they have all been brought to this strange place, even Dr. Eggman. As they try to understand what was happening, Dr. Eggman reveals that Iblis' seal has been broken. It is then that they turn and see Elise, cradling Sonic's body in her arms. After a few realizations, Eggman reveals that Solaris is about to bring about the end of the world by destroying time itself, and that it cannot be defeated in the present as it exists in all timelines. Silver refuses to give up, and suggests that they team up and destroy Solaris all at once, but Shadow quickly shoots that possibility down, stating that, with Sonic dead, Solaris is completely unstoppable.
With Amy upset over Sonic's death and their impending doom, Elise recognizes a familiar wind in the air that makes her come to believe that Sonic may not be entirely dead yet. Silver, furthering Elise's observations, explains that they can use the Chaos Emeralds to revive him. After a lengthy search on the part of Tails, Omega, Knuckles, Silver, Rouge, Amy, and Shadow, they find the Chaos Emeralds and revive Sonic, with Elise's kiss transforming him into Super Sonic. Super Sonic uses his power to transform Shadow and Silver into their super forms. Together, the three hedgehogs fight Solaris. The three use a chaos control on Solaris causing the monster to be torn apart in a time loop. Sonic, now back to normal, travels with Elise to a point in the past where they find the "Flames of Disaster" and its birth. Elise realizes that if she puts out the Flames, Solaris will never exist, but she and Sonic will never meet each other, which Sonic confirms. Overcome with despair, Elise begins to cry and shouts that she doesn't care what happens to the world as long as she and Sonic are friends. Though Sonic is clearly unhappy about this as well, he tells Elise to just smile and manages to convince her to abandon their meeting. She confidently puts out the Flames, eliminating Solaris from existence once and for all.
Time reboots back to the Festival of the Sun, only Eggman doesn't attack this time around; in effect, none of the games events ever actually happened. Elise is in her boat waving the audience as Sonic runs through the public, the "wind" of his speed making Elise lose one of the feathers in her hair. A maid asks her if everything is alright, and Elise says that she thought someone was calling her. Another maid replies that it's just the wind, and Elise says that it might be, but that it felt familiar somehow, and smiles, apparently knowing who it was. She continues with the festival as Sonic watches from a rooftop. The game ends with Sonic watching Elise's feather flying into the night, also smiling.
The events of the game were erased, although Sonic and Elise nonetheless appear to have a recollection of them.
There are three fully playable characters in this game, which are progressively unlocked by playing each character's story in the game. The player begins with Sonic; other playable characters become available when they are encountered, similar to Sonic Adventure, Sonic Advance 2 and Sonic Advance 3.
The hero of the story. When controlling Sonic, the player will get to experience high-speed, Sonic Adventure-style gameplay. He appears to have retained most of his abilities from Sonic Adventure 2. Sonic has special areas within levels called Super-Speed stages which are straight paths of high speed running. Sonic has "Custom Actions", that enables him to purchase and customize his abilities for separate situations - some of which include Sonic doing a swipe in a 360 degree formation and sliding to attack his foes. The abilities Sonic is equipped with in the Xbox Live Marketplace demo are Homing Attack, Light Dash, Bounce Attack, Grinding, a sliding kick, and a breakdance kick similar to the one seen in Sonic Battle. The Spin Dash also returns in this game, and there are new moves such as a Tornado Kick, and a Mach Speed Dash that can only be used via the 'Special Move' trigger after being purchased with rings in the in-game store. Sonic also has a whole new design for his afterimage. It looks like a blue flame now and when he attacks, and the afterimage explodes into a rainbow. Sonic can buy gems to get special powers, including a lightning shield, an enhanced homing attack, and the ability to shrink to let him jump infinitely. Equipping one of these gems changes his shoe color. For example, Sonic's normal shoe colors are red and white, but using the blue gem, in addition to giving Sonic a Mach Speed Dash, makes his shoes blue and black. Sonic is playable from the start of the game.
A black hedgehog rival of Sonic's. Parts of Shadow's gameplay seem similar to Shadow the Hedgehog. Shadow is able to drive vehicles, which include a "bike" (armed motorcycle), a "glider" (armed jet propelled machine similar to a hang glider), a "hover vehicle" (armed and capable of riding over potentially hazardous surfaces), and a "buggy" (armed four-wheeled vehicle). While in an action stage, Weapons become active for the vehicles. The Buggy and Glider gain access to Missiles,While the Bike and Hover Vehicle gain access to machine guns. He is also seen attacking with what appears to be 'Chaos Blast' and 'Chaos Spear.' It has been confirmed by the Tokyo Game Show demo that Shadow will not use firearms in this game. It has been confirmed on the Japanese website that Shadow also has "Custom Actions" and works the same as Sonic's. According to the TGS demo, Shadow can use his Chaos Spear attack and attack enemies with rapid fire kicks. He can also use Homing Attack (his has more range than Sonic's however), grind and also do a sliding kick. It has been confirmed on the U.S. website that he can use Chaos Lance (A more powerful Chaos Spear) and Chaos Blast. By defeating enough enemies, Shadow can also use Chaos Boost. Shadow becomes playable after completing the "Crisis City" stage as Sonic.
Silver is a time-traveling hedgehog who has returned to the past in order to stop Sonic from becoming the "Iblis Trigger". Silver has psychokinetic powers, which are the main feature of his gameplay. Using his psychokinetic powers, Silver is able to pick up objects around the playing field and throw them at enemies, including cars and missiles. He also possesses the ability to levitate in the air for differing amounts of time (using up his energy bar), and he too can purchase new abilities in the in-game store with rings. His energy bar depletes faster the heavier the object he is lifting, and his energy bar replenishes with time. Originally, Silver was supposed to gain an item know as the "Speed Chip", which would, as the name implies, increase his running speed. However, despite this item being mentioned several times in files found in the Xbox Live Marketplace demo, as well as being mentioned as a buyable upgrade in the Primus guide for the game, this item is not in the final game. Silver becomes playable after fighting and defeating him in the "Silver the Hedgehog" boss battle as Sonic.
- Levitate-Hold X to levitate.
- Psychokinesis-Hold R1 to use psychokinesis. Throw objects with square.
- Psycho Smash-Hold and release square near enemies.
- Psychoshock-Jump and press square.
- Teleport Dash-Press X twice quickly.
The supporting characters are companions of the main three characters (Sonic, Shadow, and Silver) who can help out from time to time in specific levels. When you meet them, you can switch to them and do things with their unique abilities that the main character cannot. Also, everyone of them, except Blaze, take part in reviving Sonic in the End of the World level (an interesting fact is Sonic and Shadow's supporting characters were their teams in Sonic Heroes). On an interesting side note, the three main characters also appear as allies in each other's levels; Silver is a ally of both Sonic and Shadow in their respective version of Kingdom Valley and Aquatic Base, and Sonic and Shadow are allies of Silver in his version of those same levels.
Sonic's best friend, and an inventor nearly on par with Dr. Eggman. Tails can use his two tails to fly and reach things that Sonic cannot--such as hitting a switch to open a door.Tails can also fly through Dash Rings that appear in some stages (as was the case in Sonic Adventure, Sonic Heroes, and Sonic Riders). He can also throw a "dummy ring bomb" that can destroy an enemy, similar to his ability from Sonic Heroes.  His flight ability can be drastically extended by releasing the (PS3)X button (360)A button before reaching max height and then holding X for about 2 seconds after he begins descending. Tails is the most playable supporting character in this game. Many fans despise Tails' Dummy Ring Bomb Move and they consider it to be a stupid ability.
Playable In: Wave Ocean, White Acropolis, Mission: The Three Musketeers, Aquatic Base, End of the World.
Knuckles is a powerful echidna with a bad temper, and he's quick to use his fists to solve any problem. Usually found guarding the Master Emerald on Angel Island, he's always willing to help Sonic thwart Dr. Eggman's latest scheme. Knuckles is able to glide and has an attack called Screwdriver, which is very similar to his Maximum Heat Knuckle from Sonic Adventure. He can also perform a move called Ground Shaker similar to his Hammer Punch ability from the 2P Battle Mode from Sonic Adventure 2. A very common glitch sometimes causes him to get stuck on walls. Another glitch allows him to complete Flame Core. This is the only way to see his victory pose on the Results screen,  since he is the only character that does not finish a stage.
Playable In: Flame Core, Mission: The Three Musketeers, Aquatic Base, End of the World.
An elusive jewel thief who also happens to be a valued government spy. Rouge journeyed to Dr. Eggman's base, White Acropolis, in search of the "Scepter of Darkness" for G.U.N, but never returned. After receiving a brief from the government, Shadow is introduced into the storyline as he sets out to find and rescue her. Rouge has the ability to make round bomb-like objects and throw them at enemies, similar to her Bat Cracker ability from Sonic Battle. She can also glide, climb, and put bombs with hearts on them into walls that she is climbing on. She also has Knuckles's climbing glitch. She has the most compulsory missions in the game out of all the supporting characters.
Playable In: White Acropolis, Kingdom Valley, Flame Core, Tropical Jungle, End of the World.
Omega is the pinnacle of the E-Series robots; he seeks revenge on Doctor Eggman for imprisoning him inside of his base. Like in Sonic Heroes and Shadow the Hedgehog he is, once again, an ally of Shadow, helping him confront the mysterious Mephiles. Unbeknownst to him, Omega has a pivotal role in Shadow's storyline and the events that unfold in the future. Omega has the abilities to both hover and shoot rapid-fire. He meets up with Rouge at the end of the Tropical Jungle stage. His hover ability can be exploited to fly without descending by tapping the (PS3)X button (360)A button repeatedly rather than holding it. He has major changes in appearance and sounds more robotic.
Playable In: Boss: Mephiles, Wave Ocean, Dusty Desert, End of the World.
Blaze is a character who plays a very pivotal role in Silver's story. Previously appearing in the game Sonic Rush, she is a queen from another world who has the power to control fire. She is very calm and introspective, a personality befitting of her rank. However, she keeps her anger bottled up inside of her, and can be very stubborn at times. She is described as a combination of Sonic and Knuckles. Her homeworld is the same as Silver's and the two share a brother-sister relationship. Both she and Silver have tried to destroy Iblis in the future, but have never succeeded. Like Tails' Extra Mission, she completely does the Wave Ocean stage on her own. Blaze is considered by Fans the Best Supporting Character in the game and ironically Blaze is faster than Sonic in this Game and in Sonic and the Black Knight. Ironically, Sonic is supposed to be the fastest thing alive and faster than anybody else (This is probably a gameplay flaw that the designers accidentally made).
Playable In: Crisis City, Wave Ocean, White Acropolis.
The self-proclaimed girlfriend of Sonic. She has a keen sense of intuition, and a fearless personality. The first time Amy meets Silver, she mistakes him for Sonic, similar to an event in Sonic Adventure 2 when she mistook Shadow for Sonic. The two end up teaming up to go on a search for the people they are looking for, unaware they're both looking for Sonic. Amy also has a connection with Elise, once Amy rescues her and gives her love advice. She can double jump, use her Piko Piko Hammer to whack enemies, and can turn invisible to sneak up on enemies. Also, she is playable in a Town Mission protecting Elise from robots, after beating the White Acropolis stage. Amy is the least playable character in the game likely due to leaving Silver after he made an attempt on Sonic's life.
Playable In: Dusty Desert, Town Mission: Protect the Princess, End of the World.
- Princess Elise - The princess of Soleanna, a town where the Sun God is worshiped, who harbors a dangerous secret. Ten years ago, the demon force, Iblis, was sealed away in her body by her father at the age of 7. The key to this seal is her own despair, which will release the form inside her. Her father, in order to protect her, urged her, shortly before his death to remain strong and never let herself cry, no matter what. Ten years later, she is a noble young princess of the age of 17. On one side, she is a prim and proper princess, but on the other, she is a confused and anxious 17-year-old girl. She tries to make light of her fate, but her encounter with Sonic is what shall truly set her soul free. Having stopped the destructive "Flames of Disaster" ten years prior to the start of the game, only she knows the secret of the "Flames of Disaster" and its relation to the Chaos Emeralds. She tells Sonic, after she is rescued, that he needs to find the Iblis Trigger. Interestingly, the Chaos Emerald in her possession was originally green , but it has been changed to blue in the final game, and her voice is different in the original trailers. Although not technically playable, Sonic carries her in the Dusty Desert and Tropical Jungle stages. Sonic still plays the same (though he is unable to use the Spin Dash or his gem-granted abilities), and he gains a new ability. By combining their powers, they can form a shield which will let them float on quicksand or deep water, which would otherwise engulf them. It is not to be confused with the traditional shields from Sonic games (which do not appear in the game), Sonic will still lose rings (or die) when attacked.
- Doctor Eggman - An overweight, mustachio scientist, equipped with legions of robotic minions. As his primary goal is to conquer the world, Dr. Eggman is the main villain in the Sonic series and in Sonic's story. He is after the power of the "Flames of Disaster", and knows about Princess Elise's mysterious power. He hopes to use the "Flames of Disaster" secret to rule the world and control time in the past, present, and, future. His appearance has noticeably changed from the style established in Sonic Adventure; he still wears his red, gold, and black Sonic Adventure attire, but no longer wears goggles as a headband, has lost most of his trademark weight (though a gut is still clearly visible under his shirt), and wears dark sunglasses with a built-in radar that can apparently detect the Chaos Emeralds. If one looks closely at him during cutscenes featuring him while the camera is viewing him from the side, he appears to have blue eyes.
- Mephiles the Dark - The main villain of the game: a creature of the mind, the will of Solaris. In order to absorb with Iblis, to "return" to his true form, Solaris, his goal is to break Elise's seal. He manipulates Silver throughout the main character's three storylines. In Silver's storyline, he is the one who informs Silver that Sonic is the "Iblis Trigger", referring to him as the "Disaster Ringleader". He assures Silver that he must kill Sonic in order to rectify his future and save his home world. In Shadow's storyline, although harboring resentment for sealing him in the past, Mephiles tries to entice and persuade Shadow into joining him to destroy the world and gain retribution on mankind for capturing and killing him in the future. Nevertheless, his methods failed to corrupt Shadow. He appears to have three forms: the first form is the original: a dark puddle-like, or gaseous form. The second form, as shown at the right, whereby he has brighter skin, this is his powered up form; the third and original form being, whereby he sports darker skin - this is the form he took from Shadow.
- Iblis - The monster called the Flames of Disaster is the main villain of Silver's story: it is the raw power of Solaris. Iblis appears to be a mindless destructive creature made of flames. It was sealed within Elise after it was separated from its other half of Solaris, Mephiles. Eventually Iblis was freed and wrecked havoc for hundreds of years until Silver's time. It was sealed within Blaze before she disappeared.
- Duke of Soleanna - Elise's father, the ruler of Soleanna. When the Solaris Project failed, the world-destroying power of Iblis and Mephiles was released. Despite being gravely wounded, he was able to bind Iblis by using his daughter, Elise, as a "vessel" body. By so doing, he was able to save the world from imminent destruction, even as he drew his last breath. He was a brilliant scientist. He also had a strong sense of patriotic and kingly duty, and loved and trusted his daughter dearly. Before he died, he begged Elise never to cry, as unlocking Iblis is in Elise's tears and despair. However, since Elise blew out the flame that was Solaris, thus erasing him from existence, "Project Solaris" never occurred, which could suggest that Duke of Soleanna may have died from another cause, or he may never have died at all.
- Solaris the Timereaver - The monster that Mephiles transforms into after absorbing Iblis, Solaris is the sun god of Soleanna. Contradictorily known as the Flame of Hope, it is said that the rage of Solaris will destroy the world.
This game features the 4Kids Entertainment cast from Sonic X in the English version while the Japanese version has mostly the same seiyu from Sonic X and the game series.
While there is no option in game to switch voices, the bios on both systems can be changed to the Japanese language to enable the Japanese voices. However, the entire game will be in Japanese, with no option to switch subtitles.
In addition to the 4Kids actors in the English version, Lacey Chabert, who is coincidentally a long-time Sonic fan, voices Princess Elise, marking the first time in the history of the franchise that Hollywood talent has provided voice-over work for a Sonic game (the 4Kids cast doesn't count, as Hollywood is a part of Los Angeles and the 4Kids Entertainment headquarters are located in New York).
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