Plot

Sonic the Hedgehog and Knuckles the Echidna, once enemies, now allies. Teamed together to stop that evil scientist, Dr. Ivo Robotnik, from taking control of the world with his crazed hover crafts and mad robots.

At the end of Sonic the Hedgehog 2, the evil Dr. Robotnik had his Death Egg downed from orbit by the heroes, Sonic the Hedgehog and his companion Miles "Tails" Prower. Having not been completely destroyed after all, the Death Egg has crash-landed on the Floating Island, taking it to the ocean below. This island has special properties - not least of which being its eponymous power of magical suspension. When Dr. Robotnik detects the presence of a massive Chaos Emerald within the island's depths, he decides to once again seek out the Chaos Emeralds so that his fallen Death Egg can regain orbit in space. Turning his crushing defeat into a sleek advantage yet again, he kidnaps Animals to convert into Badniks and created a new line of weapons. Meanwhile, Knuckles is taking his usual walk along the Emerald altar to check if the Emeralds are alright, suddenly a huge earthquake came out of nowhere, Knuckles saw the Emeralds reverberating in mid-air, stunned, he was suddenly threw into the air before blacking out. When he woke up, the Chaos Emeralds were gone, but Knuckles also saw a huge egg in the distance, surprised, he then recalled a legend of an ancient dragon sent to destroy the world in the end times, thinking this mysterious egg to be the dragon he set out, and - A giant egg-shaped figure appeared out of nowhere, calling himself "Dr. Eggman", he explained to Knuckles he had come here to study this giant egg, and that an evil hedgehog named Sonic was trying to not only interfere with his research, but steal the Chaos Emeralds as well. Knuckles, duped by the doctor, ran off to find this miscreant. Eggman smiled at himself, pleased at his ability to lie.—Sonic WIki

The Death Egg, Dr. Ivo Robotnik's space station, has once again crashed on Angel Island after the events of Sonic the Hedgehog 3. Robotnik needs power the Chaos Emeralds to power it up again, and because of this, Sonic and Tails have to find the Chaos Emeralds before him so they can stop his plans of world domination. However, Knuckles, the guardian of Angel Island and the Master Emerald, was tricked by Robotnik into thinking that Sonic and Tails are after the Master Emerald, so he is equally determined to stop the duo. But while all 3 are going round with each other, who's gonna stop Robotnik?—eduardo602002@gmail.com

The space/sky station known as the Death Egg has crash-landed into the opening of Angel Island's volcano, where it gets stuck. Picking up from where the video game "Sonic the Hedgehog 3" ended, also falling from the sky but landing safely in Mushroom Hill Zone, the titular characters continue their race to prove their opposing points: Sonic continuing to undo even more of the hostile high-tech machinations of the principal villain (Doctor Ivo Robotnik, aka Doctor Eggman), who is still pursing a dishonest agenda; and Knuckles continuing to suspect, doubt, judge, stalk, sabotage and taunt Sonic across multiple zones of the island, effectively aiding the villain. Sonic travels from zone to zone, following a pathway to Death Egg Zone. Just like the original installment of the interactive franchise, each zone corresponds to a chapter in this story devoid of dialog, narration, exposition or caption. All the way throughout this journey, the protagonist destroys robotic hostiles sent or placed by the principal villain, thus freeing the woodland animal involuntarily inhabiting the mechanical body of each hostile.

Just as with the previous installments of the interactive franchise, upon reaching the exit of every mandatory zone, the Sonic is confronted by the principal villain who with rare exception pilots a VTOL-capable aerial pod vehicle with an attached contraption tailored to the given zone's qualities and designed to injure the protagonist to the point of death. During each of these confrontations (boss fights), the protagonist defeats the villain by damaging the vehicle operated by the villain, causing the contraption to separate from the vehicle, and then the villain flees in his damaged vehicle, allowing the protagonist to free multiple woodland animals held captive in a uniform containment unit. Continuing from the video game "Sonic the Hedgehog 3", there is the additional element, whereby Knuckles sabotages Sonic in some of the zones, taunting him. Meanwhile, Knuckles may be dealing with his own set of confrontations gullibly attributed to Sonic but surreptitiously caused by the principal villain. For instance, Knuckles has been sometimes encountering and, upon every encounter, fighting with a robotic imitation of the principal villain who would condemn the imitation as a false flag; when in reality, the villain is in control of the imitation. Such is the basic formula of the events transpiring in every chapter.

Of the protagonist's itinerary, the zones subsequent to the first (Mushroom Hill Zone) and preceding the penultimate (Death Egg Zone) are Flying Battery Zone, Sandoplis Zone, Lava Reef Zone, Hidden Palace Zone and Sky Sanctuary Zone. Throughout these travels, seven pocket universes, each known as a Special Stage and devoid of active hostiles, are also visited; and from each one, a hand-sized Chaos Emerald is recovered. Just like before, given adequate energy from enough magic golden rings or so, the seven emeralds together allow Sonic to transform into "Super Sonic", meaning a condition of being impervious to all hazards except for lethal crushing forces and drowning. All this power comes at the cost of rings being depleted from Sonic's possession and the environment altogether. Utilizing the same magical mechanisms and meeting the energy criteria, Knuckles is likewise able to transform into "Super Knuckles". As implied by Death Egg Zone being the penultimate of the zones, there is also one more zone afterward, Doomsday Zone, the final of the zones. Unlike the many zones preceding them and the zone immediately afterward, the zones of Hidden Palace and Sky Sanctuary are not partitioned into acts, and each consists solely of one long scene. Together they represent a single chapter, wherein the principal villain openly betrays Knuckles and absconds with the island's Master Emerald, using the emerald's power to get the Death Egg airborne and high into the sky, while being pursued by the protagonist. The zones of Death Egg and Doomsday together represent a subsequent single chapter, the final one, wherein Sonic defeats the villain and, as "Super Sonic", recovers the emerald from outer space. Of the zones; Doomsday, unlike Death Egg but like Hidden Palace and Sky Sanctuary, consists of solely of one long scene.

Like aforementioned, the plot thickens when Sonic reaches Hidden Palace Zone. He is confronted one last time by Knuckles, but this time without any surprises, traps or absurdities, as Knuckles is simply guarding the island's emerald shrine which houses the island's Master Emerald, which ordinarily causes the island to float up high above the sea. A simple brawl ensues between Sonic and Knuckles, the latter of whom winds up being momentarily knocked unconscious. They both wind up going to the shrine, wherein the principal villain arrives in his usual vehicle with a giant robotic gripping device attached. He proceeds lock the giant emerald into the claw grip and promptly rocket away with it. Knuckles chases after the villain, gripping onto the emerald himself. Electrodes emerge from the villain's vehicle and attach to Knuckles head, and then he is jolted until he falls off the emerald and lands head first on the shrine chamber floor. The villain escapes with the emerald. From this point forward, Knuckles begins to help Sonic. In his weakened condition, he leads Sonic to a room containing an island transporter beam apparatus. They board the device and are teleported to Sky Sanctuary Zone, where Sonic fights his way to Death Egg Zone, but before he reaches his destination, he is confronted by "Metal Sonic", the tall, slender, weaponized robot made in Sonic's image (like from the video game "Sonic the Hedgehog CD"), and he defeats it to the point of disabling.

Aboard the Death Egg and upon one of its exterior bays, the principal villain operates a gigantic, anthropomorphic robotic vehicle with hands large enough to eclipse Sonic whole, three fold. The power of the island's Master Emerald, now installed within the vehicle's cranium, is being manipulated to create a directed-energy weapon, which is fired at the protagonist between cool-down periods; but the vehicle is not invulnerable and eventually sustains enough damage from the protagonist's attacks to shut down and collapse. At some point, the villain escapes in an armored rocket vessel, fleeing into an orbital field of boulder-like debris, Doomsday Zone. Imbued with the powers of levitation and propulsion, "Super Sonic" alone follows the villain into the debris, circumnavigates many obstacles, destroys many obstacles, catches up with him and tricks the homing rockets fired from the villain's vehicle into damaging the vehicle to the point where it sheds its exterior, revealing a rocket-propelled, anthropomorphic robotic vehicle (like the one from the end of the Sega Genesis Sega Mega Drive video game "Sonic the Hedgehog 2") holding onto the emerald. Sonic damages the vehicle with direct strikes, and eventually it loses its grip upon the emerald, falls apart and begins to fall out of orbit. The remainder of Sonic's superpower energy is depleted shortly after reentry into the atmosphere with the emerald. Having reverted back to his ordinary form, Sonic along with the emerald is falling from the sky, but Tails piloting the rocket-enhanced turboprop plane comes to Sonic's rescue and attaches a tow cable from the plane to the emerald.

But where was Tails during this half of the visit to Angel Island? And why weren't seven Chaos Emeralds already in the protagonist's possession from the start of this half? In the fourteen-zone combination video-game "Sonic 3 & Knuckles", which represents the proper whole story of video games "Sonic the Hedgehog 3" and "Sonic & Knuckles", two episodes of the same overall story of Sonic visiting Angel Island, Tails is present and accompanies Sonic the whole way through apart from Doomsday Zone. Also, in this complete rendition of the visit, at some point during the protagonist's travels after exiting Launch Base Zone, he enters the portal of a giant, glowing, magic pearlescent ring, which transports him to the island's emerald shrine in Hidden Palace Zone. There the seven previously-collected, hand-sized Chaos Emeralds are transformed into hedgehog-sized Super Emeralds firmly planted into shrine slots surrounding the island's Master Emerald, but these Super Emeralds have been vacated of their signature qualities in addition to the protagonist losing the ability to transform into his superpowered form. As if to recover the lost Chaos Emeralds or figure out what is going wrong with the Super Emeralds, the protagonist leaps onto one of the Super Emeralds and is suddenly transported to a Special Stage. By visiting a Special Stage for each Super Emerald and acquiring the emerald prize found there, the protagonist restores signature qualities to the corresponding Super Emerald at the shrine and gains possession of a Chaos Emerald enhanced. With the seven Chaos Emeralds upgraded by the island's Master Emerald; for the conditions whereby Sonic would ordinarily transform into "Super Sonic", he instead transforms into "Hyper Sonic", whereupon he has all the same enhanced abilities as he does in his superpowered form in addition to being faster, able to leap higher, unable to drown and surrounded by fast-orbiting sparks that destroy any adversaries within the surrounding area. Likewise Knuckles is able to transform into "Hyper Knuckles". Whereas Tails finally gains the ability to transform into "Super Tails", since seven of the basic Chaos Emeralds are not sufficient for that purpose. (This all may carry the implication that Sonic is only able to transform into anything beyond merely "Super Sonic" only when he is present on or close enough to the island: just one more of the many mysteries of the classic "Sonic the Hedgehog" universe depicted in the corresponding side-scrolling platform games.) Thus, after all of this, instead of Sonic being "Super Sonic" in Doomsday Zone, he is "Hyper Sonic" there.

The story ends with the heroes' plane returning to the island and the towed Master Emerald being dropped off there, which causes the island to float upward into the sky, before the plane heads home or to wherever Sonic and Tails were before visiting the island in the first place.