Well...yeah...let's review the stories from the past and previous games prior to this upcoming one. The stories here are from the canon Japanese manuals. And from Concept-Mobius. Great site.
First Generation
Tails Adventure (Teachnically a character spin off but whatever)
Japan
This game takes place before Sonic and Tails ever met. One magnificent day on Cocoa Island, the great inventor Tails Fox was laying outside, just taking a nap and minding his own business when he was awoke by a startling explosion and the heat of the Paroi Forest going up in flames. A flicky, who happened to be quick to find out everything that was going on, told him that the Imperial Kukku Army was taking over the island in search of the Chaos Emeralds that resided upon it. Should they get them, they would have enough power to take over the world.
Without any hesitation, our young hero ran to his house and grabbed his amazing infinite supply of bombs, and with them he went to save not only his home and his island, but the planet itself.
US
Although Sonic and Tails are the best of friends, there are times when even they needed a break not only from protecting and saving the world from the evil clutches of Dr. Robotnik but also from themselves. For these quiet times, Tails likes to retreat to Tails Island, a beautiful tropical island.
While sleeping one day on a tree stump in the forest, the robot ducks, a conquering race of ducks with a clown as a leader, began to burn down the Poloi Forest. Seeing the devastation, Tails quickly grabs some bombs and heads out to confront these evil mallards.
Sonic 1
South Island was one of Sonic's favorite places to go, and was a treasure haven of mysterious jewels and prizes anybody would desire. One of those greedy individuals being the odd Dr. Robotnik, an evil scientist who is shaped like an egg. Dr. Eggman, as he is mostly named, has always vowed to take over the world and put a stop to the nemesis that always foils his plans, Sonic the Hedgehog! Eggman decided to use the legendary Chaos Emeralds this time, using the animals of South Island, which he turned into robot slaves, to tear down the lands in search for them.
For Sonic, it was just another average day on the South Island beach. But something was different: none of his animal friends were hanging out with him! As he went searching about, he instead found vicious robots, and each time he destroyed one, his animal friends came out. Luckily, Eggman didn't know that the Chaos Emeralds can't just be found on the ground like normal jewels. They exist in another dimension, and Sonic knew just how to get them! He knew right then this must be Robotnik's treachery, so the hedgehog set right off to once again foil Eggman's fiendish plot! And he did at the end.
Sonic 2
Sonic was seen high up in the skies, manning his very own biplane, the Tornado, searching for adventure. That is until he notices a beautiful island with lush greenery far ahead that looked pleasing to the senses. With white smoke coming from the plane, Sonic flew a long arch in the sky before he immediately landed the Tornado on none other than Westside Island, the Island of Illusion! This Island, according to legend, once boasted a civilization that based their strength off of seven mythical gems, some even decided to channel the energy for their own selfish greed. But these attempts, however, came to naught.
Days had passed since Sonic landed onto the island, and during his casual exploration, he found he was being followed by a young, two-tailed fox. After spotting this admirer, Sonic noticed the little fox immediately hid behind a palm tree. Sonic shrugged it off, speeding forward into the horizon as his follower did not at all hesitate to run after the hedgehog. Instead of leaving his new follower in the dust, Sonic eventually ended up letting this fox follow him everywhere, thus starting a friendship with Miles Prower, who on the island was referred to as Tails because of his two tails that he uses as rotary blades to fly.
Our heroes were chilling on the beach, Tails was seen walking around, inspecting Sonic's plane in sheer awe. He fell in love with its curved outline and proportions, walking towards the front he then saw Sonic sleeping in the cockpit. The fox scampered towards the rear once again in hopes not to wake him. Alas, an explosion boomed throughout the nearby woods, followed by columns of flames and smaller rumbling explosions, scattered trees, rocks and sediments allover. Then, a dismal faction of marching robots came forth, cluttering the Earth.
Miles watched, shocked, yet still not realizing the full scope of the situation. Sonic watched with anger in his eyes. "Eggman...," the hedgehog muttered. In no time, Sonic sped off into the nearby wood to nail the scientist once more. After recovering from a brief faint, Tails kicked up and followed after his hero.
"DA-HAHAHAHA!!!" The loud laugh echoed throughout the woods, Eggman was nearby.
"Finally, my plan is underway! The CHAOS EMERALDS sleep somewhere on Westside Island, the Island of Illusion, so it will be easy to expel my adversary Sonic! Soon, my supreme weapon, The Death Egg, will be launched into space. Just you wait, Sonic! This time, THIS time I will gather the Chaos Emeralds, and with their power I will defeat you! Thus, I, Dr. Eggman, shall become master of this world! Daa-HA HA HA!!"
Sonic 3 & Knuckles
Sonic The Hedgehog 3 picks up right after the events of Sonic The Hedgehog 2. Sure, Sonic & Tails thought they managed to knock the Death Egg out of the sky at the end of Sonic 2, but nope. Instead, it crash landed on the legendary Angel Island, an island that was ascended high in the skies. The mountains crush, and forests are set ablaze as the impact of the Death Egg drives the Angel Island into the ocean, creating a huge tsunami.
Meanwhile, it was just a casual day for Tails. That's until Tails' emerald radar goes off, and gets readings from Angel Island. But that didn't make sense, he and Sonic still had the two Chaos Emeralds from when they were at Westside Island! Curious as to whether or not this had to do with the recent tsunami, Tails took off in Sonic's plane to check it out. Sonic, however, was just enjoying a casual lay on the beach until a strange ring washed up on the shore with an engraving on its surface. Seeing it caused him to remember about the legend of the Angel Island, which was once part of the main continent. It was inhabited by a thriving civilization who based their power off of the Mighty Stone, which is known as the Master Emerald. However, the leaders got greedy, wanting to use the power of the stone for themselves. The glory had been broken, as the supposed shattering of the stone destroyed the entire civilization, while with the test of time, a god descended and restored part of the civilization, also raising a part of the land up as what is now known as Angel Island, with the Master Emerald being the source behind its ascension.
Once Tails returned, they both got their asses in gear and set off for their next big adventure. Using the Chaos Emeralds to jet over the water, Super Sonic manages to fly onto the surface of Angel Island. The welcome wagon was not exactly welcoming, as a dreadlocked red echidna, named Knuckles, slammed Sonic by surprise and snatched the 7 Chaos Emeralds. It appears this echidna was tricked by Eggman into thinking Sonic & Tails were here to take the Mighty Stone for themselves. So while Knuckles kept Sonic & Tails at bay, Eggman was repairing the Death Egg at his self-built launch base.
Sonic & Knuckles picks up right after Sonic the Hedgehog 3. After watching the Death Egg fall once again, Tails safely flew Sonic to the ground using his two tails as rotary blades like a helicopter. The hedgehog dashed forward, only to skid to an abrupt halt upon seeing that blasted echidna thief again! Knuckles seemed to be a bit more furtive than usual, looking around cautiously before throwing the switch that closed the door he just came out of. Sonic & Tails had took no chances to just let that secret go unattended, so they just as quickly threw the switch and went inside to see this secret.
Of course, since it was a cave, it would have obviously led to a ring portal — and that's exactly what it led to! A giant, slowly spinning ring. But something was different about this one. It was not gold, but instead flashing in a radiant pastel of the seven Chaos Emerald colors. Upon jumping inside, they were directed to a strange cavern with 8 altars, the upper middle one containing a gigantic green gem. If this was not odd enough, right when Sonic landed onto the ground, the 7 Chaos Emeralds he collected would thus float above him, spinning rapidly, only to disperse high into the airspace of the cavern, and relentlessly beam down on the 7 vacant altars in bright pillars of light to show the seven Chaos Emeralds. They were devoid of their color and energy, virtually useless. Yet they were expanded in size to the point where they were almost as big as the giant green one in the center.
As Sonic jumped on top of the first colorless emerald, he would just as quickly be warped to an alternate dimension where he managed to achieve the true power of that particular emerald, as the energy concentrated within the gigantic gem, restoring its power and color, thus creating what is known as a Super Emerald, the stimulated, supercharged, and much larger form of a Chaos Emerald. After repetitive run-ins with these special flashing ring portals, Sonic & Tails managed to restore the power and saturation of all of the 7 giant emeralds, thus collecting the 7 Super Emeralds. Sonic used this to his advantage while he was hot on Robotnik's heels, using their power to morph into HYPER SONIC as often as he could, an even faster, more lethal version of Super Sonic, evident by his fur flashing the 7 pastels like the flashing rings, and radical speed and destruction capabilities.
Before they knew it, Sonic and Tails once again handed Robotnik's *** to him on a silver platter, right at the volcano the Death Egg landed in, chasing after him into a strange, underground palace known as the Hidden Palace. Alas, they would once again run into Knuckles right in front of a mural depicting oddly familiar imagery, but this time it was Sonic & Knuckles one on one. Not just some run in where Knuckles pushes some button causing them to fall and then he runs away. This time, it was personal! Sonic thus gave a whooping to the rad red echidna he wouldn't soon forget. While the echidna lay exhausted on the ground, Sonic & Tails ran over to a very familiar area. It was the same cavern they were continuously warped to by the flashing ring portals to collect the 7 Super Emeralds! All 7 of them glowed furiously in their special colors, but Eggman was also there in that egg mobile of his.
Surprisingly, Eggman had no concern for the Super Emeralds. He wanted the giant green one in the center. That green one was the Master Emerald, the emerald that kept Angel Island floating above our heads, and was the emerald that controlled the Chaos Emeralds. Using a suction device, Eggman heaved the giant Master Emerald from its altar. Knuckles tried to stop him, but was thus fried by shocking nodes that Eggman deployed out of the eggpod, and then busted a large hole through the ground as Knuckles fell through and down into the pit, landing onto the ground with a rather mean thud. Eggman got away, there was no time to lose for our blue and yellow heroes! Sonic & Tails immediately leaped down into the pit, and were alas stuck by a thick door. But it was nothing Knuckles couldn't handle. Knuckles was tricked, he knew it. Right from the very beginning when Eggman told him that Sonic was the one who was going to steal that Master Emerald, and that he meant to help Knuckles. Knuckles' gullibility got the best of him again. He had to right this wrong.
Knuckles eventually recovered from his heavily sustained injuries, but not by much. He stood up, ran over to the door and beckoned for Sonic & Tails to follow. Using those fists of fury, Knuckles effortlessly punched the door into tiny fragments, running towards a warp device that transported the three heroes high into the skybound ruins of Angel Island. Knuckles was in no condition to follow them; his last shred of help consisting of no more than ensuring their onward path through these ruins, as he lay on his hands and knees, panting in defeat and shame.
Sonic & Tails had to get going, thus trailblazing through the mossy, vine-covering highways only to run into an old friend: Silver Sonic, upgraded into a new, more streamlined and lethal version: Silver Sonic Mk. II (or Mecha Sonic Mk. II). Of course, a bit later — boom, it's dead. As Sonic & Tails ran their way up a crumbling spiral runway towards the ascending Death Egg, Mecha Sonic Mk. II fell towards Angel Island in the crumbling Sky Sanctuary, which was pretty much its final fall. Meanwhile, Sonic & Tails for the second time boarded the Death Egg, this time for a much longer period.
Sonic & Tails had to trailblaze through the entirety of the massive, not to mention quite dense space station, only to meet up with Eggman in none other than a second, upgraded version of the oversized Eggman-shaped mech, this time using the Master Emerald as a powersource to shoot hordes of flames and gigantic energy beams at our two heroes. But with their quick and agile tactics, Sonic & Tails bested the giant Eggman mech. The resulting explosion showed Eggman getting away with the Master Emerald in his Eggpod. Sonic couldn't take any more of this chasing, thus morphing into Hyper Sonic to chase after Eggman who was getting away in a smaller version of the Egg-mech, covered in heavily-fortified blue armor.
It was now a chase between hero and villain in the meteor fields around Soniworld. Impervious to damage, unnaturally agile, and quick to trot, Hyper Sonic managed to once again lay the smackdown on Eggman, disposing of the armor only. Eggman then made his final attempt to get away in the smaller egg-mech, holding the Master Emerald and trying his best to bombard Sonic with everything in his arsenal. Someone is quite determined, wouldn't you say? Maybe Sonic SHOULD give Eggman a shot at controlling the world. It takes a man with determination like that to have the responsibility to control a planet!
No avail. Hyper Sonic busted that thing into cosmic dust as well in the end, thus obtaining the Master Emerald and zooming down back into the atmosphere of Soniworld, catching up with Tails and the Tornado. They returned the Master Emerald to Angel Island, and it was soon lifted back into the skies, and was given a grateful thanks from their supposedly new friend, Knuckles! All was once again well at these parts.
Sonic CD
On a certain month of every year, a tiny planet appears in the skies over the Never Lake. This small planet is none other than Little Planet, AKA the Planet of Miracles. Little Planet is home to 7 mysterious jewels that can altar the passage of time. If all of them are collected, miracles are sure to ensue: deserts turn to lush jungles, and murky waters purify! But of course, there is a very certain mad scientist who has other plans for these gems. Once the planet appeared, Dr. Robotnik immediately bounded the tiny planet to a giant mountain with his face carved in it, linked by a huge chain. Dr. Robotnik then wasted no time in high-tailing his butt over there to take control of Little Planet's past so he will then have complete control over it in the future.
Sonic was seen rushing through the plains before he would then spot the Little Planet chained up to the mountain. And upon seeing the wicked carving of Eggman's filthy mug along its surface, Sonic knew exactly who the perpetrator was. So the hedgehog immediately went dashing up the chain and to the planet to rip Eggman a new one. Problem was, Sonic didn't even know Eggman was up to this until that very point, so Eggman had quite a lot of time to prepare.
Meanwhile, back on Sonic's world, a young hedgehog girl by the name of Amy Rose was using her tarot cards to predict her future. They tell her that she will meet her idol, Sonic, on the Little Planet. So needless to say, she packed up and hauled pink hedgehog fanny over to the Little Planet as well. However, once Eggman finds out she is there, he finds she is the perfect target, sending out his new metal duplicate of Sonic, Metal Sonic, to go out and catch her, and that it did. Metal Sonic captured Amy right before Sonic's very eyes, making off with its new hostage. Sonic then knew it was up to him to save her and stop Eggman at the same time!
SegaSonic The Hedgehog
Sonic and his new friends Mighty the Armadillo, and Ray the Flying Squirrel seem to have been captured by a giant machine that is shaped like Eggman's face, and now they must escape from his base on Eggman Island, and at the same time, perhaps destroy it all.
Knuckles Chaotix (Teachnically a character spin off but whatever)
It's been a few months after the events at Angel Island, and Sonic & Tails were up to their normal thing. As for Eggman? He was already unfolding his next fiendish plot to take over the world! And what luck, since a recent earthquake that was triggered by the Master Emerald caused the unveiling of a new island that rose from the waters. The island's relationship with the Master Emerald was quite potent, since its once drenched, rocky surface was suddenly turned into lush greenery and beauty. But of course, why make things green and lush when you can make them metal and morbid? Eggman took immediate advantage and went off to investigate this newly arisen island. At the same time, Knuckles also notices the new island, and goes to investigate as well, under the impression he might find out about his past and the ancient echidna civilization. Unfortunately, Eggman was waaaay ahead of him.
On his journey of scrutiny, Eggman would thus come across an odd ring. Carved into its surface was text that confirmed that this island was indeed part of the aforementioned lost civilization. A bit later, he came across yet another ring, which was one of the Chaos Rings: 6 special rings that were united with the Master Emerald to create a dimensional space within the ring that is filled with the power of the Master Emerald. Upon studying the ring, Eggman concludes that he can use it to summon the Master Emerald. And so his plan begun, quickly building his usual base of operations in the form of a giant, carnival-themed fortress along the surface of the whole island, aptly named Newtrogic High Zone.
Knuckles eventually arrives, only to see that he is all too late. Eggman has utilized this special ring energy to create such doo-dads known as the Dark Ring and the Combi-Confiner, which he used to freeze any opposition in time. This dreadful event had already come to pass upon the unlucky souls of Vector the Crocodile, Mighty the Armadillo, and Charmy Bee. Knuckles was just in time to save a chap by the name of Espio the Chameleon, however. So with his new chameleon of a partner, the two go off to save the rest of their friends, and thus this new island before Eggman finishes off his plan!
Sonic 2 GG
After all the stuff Dr. Robotnik pulled last game, South Island is peaceful. Naturally, that poses a problem for the Blue Blur: What to do now? Luckily for him, a note was left for him by his new best bud, Miles "Tails" Prower. Apparently, the kid's been fox-napped by the Eggman, who in turn is demanding the Chaos Emeralds (6 again, for some reason) as ransom. Sonic just skims through the paper before zooming off to his next adventure, angry at Robotnik for taking Tails and grateful for ridding the hedgie of his boredom.
Tails Skypatrol (Another character spin off but whatever)
Tails' Sky Patrol is about how Tails decides to take a vacation away from all of the hustle and bustle of hanging around with the blue hedgehog who just can't seem to sit still. Instead, Tails goes off to search for his own adventure, and that he does.
In time, Tails stumbles upon an old, uninhabited island that is covered by a long railroad that stretches along the entirety of the island. Upon hearing a rumble on the tracks, Tails quickly runs and takes refuge behind a nearby bush. Zooming past was an old witch in a minekart as she zoomed down the tracks. Turns out this old hag claimed this island for herself, and threatened to turn any oppressors or trespassers into crystal with her black magic. Once she left, Tails then decided it was time for him to make things right...
Sonic Labyrinth
Dr. Robotnik has finally done it! He has figured out why Sonic kept beating him over and over again. It is his speed (took him long enough, right? And he is supposed to be a genius)! Now, what way is there to reduce the speed of his azure arch-adversary? Well, since he is a genius, he could slow down Sonic's molecules to a crawl or something. No, instead Dr. Robotnik, sneaking into Sonic's room in the middle the night, glancing at the innocent and totally unprotected blue hedgehog with his nefarious eyes and malicious intent firmly planted in his mind....and he replaced his sneakers with some heavy ones. BRILLIANT! (I am imagining the guy from the Guiness commercrial. Try to. It makes it funnier).
That morning Tails happened off on some sort of adventure thing (perhaps a Tails Adventure if it is the US version), our blue hero awoke with a big old yawn and reaching under his bed he pulled out his sneakers and threw them on his feet. Somehow when he was putting them on he did not notice their weight, because now they were so heavy he could barely even run. Dr. Eggman laughed because Sonic had thrown on his patented Speed Down Boots, and the only way to get them off are with the Chaos Emeralds. However, Sonic had the last laugh because he found out somehow (whether he tried or just fell down the stairs) he could still Spin Dash. So off our hero went with that knowledge in mind, to the Great Labyrinth in order to gain these magical jewels so that he can run again.
Sonic Chaos
...Yet another storyline that involves the Chaos Emeralds. This time, Robotnik has gotten them all and sent all but the red one into other dimensions. If Sonic and Tails don't get the Chaos Emeralds back from the other dimensions and get the red one back from Eggman, or else the island drops into the ocean as a result of the flux in the dimensions between the emeralds. Go Sonic!
Sonic Triple Trouble
Dun dun dun. You gots three peeps on yo' tail, Sonic (or tails, Tails. Ha! I am so not funny at all). Dr. Robotnik wants the Chaos Emeralds (...yeah yeah, so what is new? Dude, this guy has to get another hobby), but this time not only does he already have one but he has also tricked the guardian of the emeralds, Knuckles the Echidna, to believe that Sonic is out to take the emeralds from him for some malicious intent or something. NOOOO!!! Say it ain't so! Knuckles?! TRICKED?! Pfft. My 4 year old cousin could trick that egg-laying mammalian.
New to the story, however, is a rogue agent, Fang the Sniper, who is out to get the emeralds for the most mundane of purposes. Profit. Finally, Sega has a character that wants the emeralds for a viable reason. And as it so happens, although he is supposadly slower than the rest of them (Eggman rejoice, someone actually runs slower than you), he has that nifty little bike, named the Marvelous Queen, that is apparently fast enough to ALWAYS beat both Sonic and Tails to the emeralds. It's an amazing thing, really.
Sonic's (or Tails') job is a simple one. Beat Robotnik and get his emerald, rescue Knuckles from Robotnik's trickery and grab the emeralds before Fang can or else the only way you are going to get them is by laying out a huge sum of moolaa to a dealer in the black market.
Sonic 3D: Flickies' Island
Flicky Island is home to the rare Flicky Birds, which are apparently closely related to the Chaos Emeralds, which intrigues Sonic into investigating. Eggman immediately took this to his advantage as well, also finding out that the Flickies are rarely seen because they live in a parallel dimension and teleport through ring portals. Using his new Dimensional Ring Generator, Eggman takes the Flickies from their home dimension and turns them into mindless robots.
Sonic arrives to see all of his Flicky friends turned into robots, so it was up to him to save them from the wretched hand of Dr. Robotnik, while getting those blasted jewels along the way!
Sonic Blast
Shortly after the incident on Flicky Island, a most unusual island has risen out of nowhere in the ocean. Its shape, however, was all too familiar: Eggman's filthy mug! And standing tall upon this newly arisen island is Eggman's Silver Castle, with which he is planning to continue his quest for global domination. Sonic & Knuckles band together to put this island back into the murky depths where it belongs, but unfortunately for them, Eggman saw their arrival coming, so he rigged his new base of goodies with some extra-dangerous traps…
Sonic Drift
After turning several parts of the zones of South Island into raceways, Dr. Eggman challenges Sonic, Tails and Amy to a race to determine who gets the Chaos Emeralds, and so began the first Chaos Grand Prix!
Sonic Drfit 2
The next annual Chaos Grand Prix has finally arrived, and this time, more raceways have been made, and even more of Sonic's friends (and foes!) have joined in on the action!
Sonic R
Their adventure had continued on, but soon our heroes Sonic & Tails would come across a monitor on a building. The monitor was displaying footage of a recruit advertisement for the World Grand Prix, the race to figure out just WHO was the fastest of them all. Surprisingly, Sonic was not all too wild about the event, even with Tails incentive convincing. Alas, Dr. Eggman's name shows up on the list of racers who have already signed up. Sonic's decline just as quickly turned into an acceptance.
After hearing Sonic joined up, Knuckles joins to rival the blue blur while Amy joins for reasons obvious to the knowledgeable at heart. Eggman joined because he found out that the Chaos Emeralds were hidden along the routes of the World Grand Prix. While he is ready to dispatch some of his newest devices of disaster, he decides to let Sonic find the gems for him. A risky course of action, and more than likely ineffective in the end.
Sonic The Fighters
It was only a matter of time after the destruction of the Death Egg that Dr. Eggman would thus begin construction on a superior model, the Death Egg II, which was just as quickly launched up into space. As soon as it began its orbit, Eggman dispatched a swarm of Egg-Robos to reek havoc upon the innocent creatures of the world. Tails' reconnaissance robot manages to pick up signals from these bogeys, and also managed to transmit images of this new Death Egg II right to Tails' workshop.
To stop Eggman's evil plan, Tails constructs the Lunar Fox, a rocket ship that should be able to reach Dr. Eggman's Death Egg II. However, it's only a one-seater, and requires the power of 8 Chaos Emeralds. Now, obviously Sonic would be the best candidate for this, but it turns out the Chaos Emeralds are separated among 8 individuals, and they all want their chance in the spotlight. So there is only way to determine who is the strongest, and most suitable for doing such a heroic deed: a fighting tournament!
Second Generation
Sonic Adventure
Approximately 3000 years ago, times were rough because of the political incompetence and conflict that seemed to never have ended. All of this was between a group of echidnas who were once a tribe of mere bullies. But under the leadership of Chief Pachacamac, they rose as one of the most notorious and all-feared forces of war ever known. Chief Pachacamac had inherited the throne from his mother, who did not seem to fancy his war-mongering disposition. His greed for power caused him to overlook merely restraining any considerable opposition, since he could instead rule the world. This insatiability led him right to the shrine of the 7 Chaos Emeralds.
Unfortunately for Pachacamac, his daughter Tikal, and a mysterious elemental water spirit were in his way from achieving this goal. His daughter was brought up by his grandmother, who passed on her pacifist teachings and mythology of the echidna tribe. Tikal did not at all approve of her father's aggressive attitude, and senseless lust for power, especially after befriending this mysterious water spirit, who was the guardian of the small chao that frolicked around the Emerald altars. On a gloomy night, her father and a group of warriors arrived at the shrine to take the Master Emerald. However, they were stopped by his daughter, who begged them to stop. Careless and ruthless at the same time, Pachacamac ordered his men to charge. They trampled both his daughter and the chao, running towards the emerald altar. Before they got to their prize, they were intercepted by the water spirit who now took a physical form. It absorbed the power of the Chaos Emeralds and turned into a giant monster, destroying the entire echidna civilization. Luckily, Tikal managed to get to the Master Emerald after she woke back up, and recited an ancient spell that trapped her spirit, along with the water spirit's, in the Master Emerald. It was at this point that this water spirit was named Chaos, and the 7 Emeralds were named the Chaos Emeralds.
Only a handful of echidnas survived this tragedy. They made it their rightful vow to guard the Master Emerald so that the horrid monster from within will never be set loose upon the world again. The chao that were also decimated to a near-point of extinction eventually began to multiply in numbers in the test of time. Some 3000 years later, at the current time, unbeknownst to the severe risks and threats of his ulterior motives, Eggman sets out to free this beast and use it for his own lust for power.
The good doc now has his sights set on Station Square. He plans to destroy it, and on its ruins build Robotnikland (AKA Eggmanland in Japan), the "ultimate" city. After discovering an ancient tablet in the nearby Mystic Ruins, which interpreted the tale of Chaos and the echidna tribe, Robotnik decides to use this beast to perhaps help build Robotnikland. Already, he's planning waaaay too far ahead; never thinking of the cons of his actions, such as Sonic and his pals, but most of all, how does he think he'll get this beast to obey him?
Sonic Advance
Simply put, it's the same old thing. Robotnik wants to rule the world. He wants the Chaos Emeralds. Sonic and Co. have to stop him. The storyline is practically the same as Sonic 1's besides the three other characters joing with Sonic to stop the madman.
Sonic Shuffle
Maginaryworld, a dimension compiled entirely of the hopes and dreams of all. At the center of this psychedelic madhouse is none other than what is known as the Precioustone, a jewel that is the very incarnation of all of the hopes and dreams. Guardian of this gem, is the Goddess of Dreams, Illumina, while what seems to be her apprentice, Lumina Flowlight, is an additional guardian.
Of course, in the Sonic series, gems seem to be the ultimate goal for any do-badders in the local vicinity, and in this case, it was an odd-looking (actually pretty cool) creature known as Void. For no apparent reason whatsoever, Void finds it necessary to shatter the Precioustone to pieces. Without the Precioustone's power, Maginaryworld's very existence is now at stake — naturally. Even worse, the 2-bit, good-for-nothing Illumina vanished because of this loss of the Precioustone. So it was up to the little pink fairy chick to save this imaginary dimension that actually exists within the mind of some Japanese dude.
So, what does Lumina decide to do? Well, she decides to reach out to those in all other dimensions. Sonic, Tails, Knuckles, and Amy happen to be the ones who are chosen to perform this most noble of tasks. Unbeknownst to our heroes, who obviously accepted, Dr. Eggman caught onto their game with his eyes on the Precioustone as well, which at this point was in pieces that were scattered across all ends of Maginaryworld. So the chess pieces have been set (it's a shame I can't say the same about the subpar simulation of Chess seen in several of the mini games in this abomination), and the action begins here!
Sonic Adventure 2
50 years ago, the president (13 presidents ago from the current one) began to form a large interest in what was known as mankind's eternal dream: researching immortality. This drove the president into confidentially requesting Professor Gerald Robotnik (Dr. Eggman's grandfather) to scrutinize such a farfetched illusion of grandeur.
Gerald Robotnik stubbornly refused this request, since it had crossed Man's limits. He was a man of ethical standards (unlike his grandson). However, ironically, Gerald's beloved granddaughter Maria had been diagnosed with a lethal sickness known as NIDS (Neuro Immunodeficiency Syndrome). Medical treatment for this illness at the time was unavailable. This eventually resulted in Gerald Robotnik's approval of the president's request, thus research for immortality begun aboard the ARK, a spherical space research facility. Research on Maria's illness was being conducted thoroughly, but Gerald's newly unveiled research on immortality brought in a new ray of hope. Could something so absurd have been fabricated within the mind of Gerald Robotnik? Soon, the project underwent research and was codenamed Project: Shadow, named because of the sarcasm involved in not actually being able to create a shadow (which didn't exist in the world).
At the beginning stages, Chaos Emeralds were researched and soon resulted in the creation of Chaos Drives. These Chaos Drives were the objects in which the infinite power of the Chaos Emeralds were utilized upon a living being. They were meant primarily for the prototype, which had to be nearly perfect before toil on the main project would commence. The prototype of the Ultimate Life-form bore fruit. It was modeled after a lizard's shape, and seemed to meet many of their standards: it could self-regenerate, self-restore, and self-reproduce. This thrilled the researchers. However, in their moment of glory, things began to look bad. The prototype was unruly, and hard to control. This caused many problems for the researchers, and those aboard the Space Colony ARK as a whole. More than likely, because of the threat this posed, the confidential research had been leaked into the GUN military organization back on Earth.
The GUN's top ranking officials had developed a strong disliking for the researchers aboard the ARK, and thus planned to take advantage of the ARK's situation and form a plan to shut the ARK down. This secret plan was named "ARK's Indestructible Seal." The plan included the evacuation of all citizens of the ARK back to Earth, while all research facilities involved with Project: Shadow were frozen and shut down, and all of those involved with the project were to be killed. This entire plan was released to the public under the premise that a bio-hazardous accident had occurred that GUN knew nothing about, and those who were killed (namely the researchers) were victims of the accident. This was to cover GUN's true motives of shutting the ARK down, erasing Project: Shadow, and put the blame on Professor Gerald Robotnik as the person responsible for the accident. The plan was completed in 7 days, and the prototype of the Ultimate Life-form was found and sealed within the deepest part of the colony.
However, there was a miscalculation in their plan. Unbeknownst to GUN, Gerald was putting the finishing touches on the Ultimate Life-form, "Shadow," using a much more desirable interface and physique for the creature. As they stormed into the space colony, Gerald escaped, and entrusted the final project (which was in a stasis tube at the time) to his granddaughter Maria, expecting her to release the project, and herself in an escape pod towards the planet. Although she managed to successfully release the project, she was gunned down by GUN officers before she could escape.
Gerald Robotnik was jailed at Prison Island back on Earth, and when he saw Maria's name upon the list of casualties from the "accident," he went insane. It also happened that GUN managed to retrieve the Project: Shadow that was released via Escape Pod (or it could have been another one). Gerald somehow managed to altar the Ultimate Life-form once again with a new motive. His mind was set totally on revenge, and he programmed Shadow with those same intentions. Gerald was eventually executed soon after.
50 years later, after performing extensive research on his grandfather's legacy, Dr. Eggman then decides to use this Ultimate Life-form for his own biddings, hoping it would do better than Chaos did. It was only a matter of time before Dr. Eggman managed to penetrate into the GUN Prison Island and release what he had sought out for: Shadow the Hedgehog. However, Eggman seemed to have freed a whooole lot more than what he had bargained for…
Sonic Advance 2
Ok, guys, you know the drill. Stop Robarfnik from getting the Emeralds. This time, though, the Eggman's resorted to kidnapping again. He's taken new friend Cream, Tails (again) and duped Knuckles (AGAIN). In Cream's case, though, she gotr accosted for trying to save her mom, Vanilla from a similar fate. And this adventure is about to get running for the hills for the scientist...literally.
Sonic Heroes
Tails and Knuckles finally catch up with Sonic as he tours around the globe, and pass him a letter from his arch-nemesis Dr. Eggman, threatening another outrageous revenge scheme. This time, the deranged scientist announces that he has finally completed his ultimate weapon, and in a matter of three days, he will be ready to bring the world to its knees! Unlike Tails, disturbed by the message and unsure what will happen, Knuckles relaxes, confident that there's nothing to worry about. Sonic, however, shows a brief flicker of a smile and takes off again into the distance. With that familiar grin of confidence, Sonic says he wouldn't miss this party for the world! And this is how the three reunite for their next adventure to put an end to Dr. Eggman's wicked ploy as Team Sonic!
Meanwhile, treasure hunter Rouge one day hears that Dr. Eggman is accumulating a massive treasure collection. She immediately heads for Dr. Eggman's headquarters to liberate these riches, but discovers the base abandoned with all of the valuables gone. However, she comes across a stasis capsule that to her surprise houses the figure of Shadow. Far from being deceased as everybody thought, he was indeed very much alive, but unconscious. In order to release Shadow from the capsule, Rouge switches on the facility's power, unintentionally reactivating the final E-Series robot, E-123 "Omega." Shadow wakes to find his memory gone, unable to recall why or how he went into stasis. Omega, on the other hand, was rather upset about Dr. Eggman shutting him down. Mistaking Shadow for one of Eggman's robots, he immediately starts to attack him. Rouge steps in to break up the fighting, and reminded them both that their enemy is Eggman, the three shook hands and Team Dark was formed.
Amy, crazily in love with Sonic as always, is concerned that she hasn't had any contact with him for over a month. Making little progress on his trail, she is about to give up hope when she catches sight of Sonic's picture in a newspaper. In her excitement, Amy runs straight to the publishers to ask where the picture was taken, and on her arrival, she meets a huge, familiar looking cat called Big, and a cute rabbit named Cream that we all know and love (mostly hate). A quick exchange of stories reveals that Big is looking for his best friend Froggy, and Cream is looking for Cheese's twin Chocola, both of whom had appeared in the picture with Sonic. From this, they decide to continue their search together as Team Rose.
And hey, the Chaotix boys were in on this new scheme too! Been awhile since they got involved with anything. The Chaotix Detective Agency is always at your service if the price is right. Lately, however, things have been quiet with very little work available. But one lazy day, a mysterious package is delivered to Chaotix, and inside they find a transceiver which mysteriously promises a handsome payment if the Chaotix will take on a case. Charmy is thrilled by the offer, but Espio remains skeptical due to the strange nature of the communication. Boss Vector, with dollar signs in his eyes, wastes no time in gathering his troop together as Team Chaotix to take hasty advantage of the opportunity.
So off Team Sonic, Team Dark, Team Rose, and Team Chaotix go to accomplish what they had set out to do. However, unbeknownst to them, it wasn't Dr. Eggman who was really behind all of this, but instead an old face our friend Sonic thought he would never see again…
Shadow The Hedgehog (Another character spin off but whatever)
Shadow is still troubled about his lack of memories. He has gained one, though. Unfortunately, it's breif glimpses of Maria's death, though he doesn't know it's her. One day, as Shadow was pondering all this, the sky darkened with a red shade and out come an army of red and black ailens who quickly begin to smash the living crap out of everything. The Black Arms has landed on Earth, in retribution for Dr. Eggman's recent invasion of their digs. Poetic justice, I suppose. Either way, Shadow could care less, and walks off. Before he does, though, his name is called by a sinister voice. He turns around to see an ugly looking eye projecting the image of the aliens' apparent leader, Black Doom. The ruthless ET wastes no time giving our (anti)hero a message:
"As you can see, the day of reckoning will soon be here. Find the SEVEN Chaos Emeralds and bring them to me as promised."
Naturally, Shadow doesn't know what the heck this jerk's talking about or how he knows who Shadow is. Black Doom doesn't explain, though. As he leaves, Shadow is left with even more questions: Who was that guy? And how does he know Shadow? He does, however, deduce one thing: the Chaos Emeralds are the only way the Black Blur's getting any answers. That being the case, Shadow he Hedgehog begins his most important journey ever.
Sonic Battle
Well, for once, there's a 2D Sonic game with a fleshed-out story. Dr. Robotnik, stubborn old coot that he is, just won't let his grandpa's sleeping dogs lie. It seems that Gerald, while working on Shadow, was experimenting with a mysterious robot known as "Gizoid". The Eggman finds it and decides to use it to do his bidding. Only problem: the stupid thing jsut ignores him. And absorbs a Chaos Emerald to boot. After being fed up with the thing, as well as copying its tech to make one that listens (E-121 Phi, yet another entry to the long forgotten E-Series), Robotnik tosses the bot on the beach.
The next day, Sonic, suffering from boredom AGAIN, finds the previously mentioned robot and decides to take it to Tails for some fixin'. Shortly, the mech, whom Sonic names Emerl, meets up with the rest of the cast and learns from each furry. There's still a lot more to "Emerl" than meets the eye, though. Oh, and there's fighting. LOTS of fighting.
Sonic Advance 3
This time around, the story ties in with Sonic Battle somewhat. Dr. Robotnik's built a new robot called G-mel (yeah, yeah, I know. Hush.) THEN he lets loose some Chaos Control on the planet, cutting it into, you guessed it, seven sections. Sonic & Tails take it upon themselves to find the others and fix this stuff. (At that point, the storyline goes on once you start playing the video game).
Sonic Rush
Basically, Eggman's up to his usual tricks, or at least Sonic assumes he is as he races through the forest, eliminating the Egg Pawns in his way. Finally he comes across Eggman, and with a quick butt kicking session, Eggman beats a retreat, leaving behind a mysterious jewel, similar yet different from a Chaos Emerald. As Sonic moves in to inspect the Jewel, a mysterious cat swoops in and grabs it, saying something about finding the second one. She thanks Sonic for beating Eggman for her and dashes off. Who is she? And what was that gem? Play and find out.
Sonic Riders
At midnight one evening in Metal City, Sonic and friends uncovered a valuable Chaos Emerald. As they stood admiring it, a mysterious trio on floating Extreme Gear appeared out of nowhere and snatched the precious gem. As they raced away, one of them dropped their airboard and Sonic jumped aboard to pursue the thieves. But unaccustomed to riding, he lost his footing and the they got away.
Later, as Sonic and friends gathered in Metal City plaza, they were interrupted by Dr. Eggman speaking from a giant building monitor. "I've put together a little extra something to spice things up! I call it the 'EX World Grand Prix!' A tournament to see who is the best of the best with Extreme Gear!" Eggman stated.
Sonic groaned with disdain… "Eggman again! Just what is he up to this time?"
At that moment, the three mysterious Chaos Emeralds thieves appeared as top ranking entrants on the monitor and Sonic's attitude changed. "The EX World Grand Prix, huh? Let's do this!" Sonic said confidently.
Sonic's mind was made up. But just what is Eggman really planning? And who are the three mysterious characters?
And...were're about to enter the third generation of games.
