In one of Eggman's abandoned factories, Cubot and Orbot are lounging around watching old TV, having lost the cable a while ago.
They're bored out of their wits since Eggman "drifted off into space". Orbot contemplates switching to Sonic's side since he seems like a fun dude to hang out with.
Then Eggman makes a grumpy return, chiding Orbot for being another traitorous robot. Orbot and Cubot spring to attention, surprised that he has returned.
Eggman doesn't comment on his return and instead is quick to get to work on his next plan. When questioned how this will be different form the rest, Eggman proclaims he has found the answer.
The key to defeating Sonic the Hedgehog is to remove his friends from the equation so he won't have anyone to support him.
But he won't kill Sonic's friends. No, he has a far more diabolic plan in mind.
He then snaps his fingers to summon Metal Sonic, who grapples Orbot and Cubot, dragging them along with him to work on a new machine.
Then, in solitude, Eggman walks up to a strange ring and grins, saying he's prepared to unlock its secrets...
Meanwhile, Riku is flying through space once again, conversing with Takashi to pass the time. His journey is stopped when he finds another Earth, which should be impossible.
Though really, its not THAT strange, given his time in the Metroid universe. Nevertheless, Riku decides to investigate.
He winds up taking in the strange greenery and birds and realizes that he's on Sonic's world now. And soon after realizing that, he came across the blue blur himself.
Sonic speeds back and talks with Riku, figuring out he's not of this world from his type of shoes. Though Riku lies about it for a bit, he does eventually tell the truth.
Then, while being challenged to a race by Sonic, Riku asks him if there's been any trouble on this world lately.
Sonic says its been quiet since his birthday, sadly. Riku pulls ahead of Sonic momentarily but the blue blue kicks up the pace in confidence.
Their race around the world winds up turning disastrous when Riku's speed drags cars and parts of the street up in his wake.
He does stop them without any harm done to the people around, but this act of destruction forces the race to end.
Riku's embarrassed to admit that he doesn't have good control over his speed. Sonic says he could probably fix that with Tails' help, so they decide to head on out to his workshop.
After a quick scenic detour through some of the places Sonic's been to, they arrive at Tails' Workshop in the mountains.
There Riku introduces himself to the yellow fox, and him and Sonic do the same more formally.
Riku explains what his deal is to Tails and Sonic and Sonic's pretty stoked to meet someone from another world again. He reminisces a bit about the Subspace Emissary before Tails snaps him out of it.
Tails promises to fix up Riku's shoes so he can run fast. In the meanwhile, Sonic goes to take another run or two around the continent.
Tails and Riku hit it off pretty quickly talking about space travel and multiple Earths. Turns out that there's some similar history between both Earths regarding their games being made, despite obviously different circumstances behind them.
Tails then hands Riku his shoes back, having applied a gelatinous material that can counteract friction with the ground.
Suddenly Sonic bursts back into the room and tells of something exciting happening outside, much to Tails' concern.
They pop outside and find a giant floating battleship waiting for them up above. This is Eggman's latest creation, even bigger than the Final Fortress.
Declaring his triumphant return, Eggman prepares, YET AGAIN, to create his Eggman Empire.
He boasts that Sonic won't even be able to REACH his latest creation, the Egg Continent, for he has in his hand the ultimate power.
A capsule drops before the group, releasing Shadow the Hedgehog, who appears to be in a daze of sorts, and surrounded by a creepy purple aura.
At Eggman's command, Shadow starts attacking Sonic, angrily telling him to stop hurting Maria.
Sonic tries to call him out for losing his mind but Shadow doesn't seem to respond to what he's actually saying. In his head, Shadow sees Sonic trying to kidnap Maria and give her the freedom she always wanted back on Earth.
Sonic and Shadow scuffle but its obvious the ultimate life form isn't going to back down easily.
It gets to the point where Shadow drops his inhibitor rings, forcing Riku to jump in and help out. With his help Sonic is able to break the control over Shadow.
However, Shadow is now pissed for other reasons and very nearly destroys Riku with Chaos Blast before Sonic jumps in.
Shadow snaps out of it but is greatly confused how he got here. Tails comes to help, explaining that Shadow was being controlled by Nega Hyper-go-on energy, much like how Tails briefly was a while back.
Shadow says that it was like he was compelled to hate Sonic, even if his mind had to make something up to do so.
This can only mean Eggman's modified the energy, and who knows what else he'll do with it. Sonic and Shadow then hop on Tails' Tornado while Riku takes flight. The four of them make a quick trip to the Egg Continent, ready to foil Eggman's latest scheme.
Onboard the Egg Continent they find out that Eggman's glued the Final Fortress to the end, just to emphasis just how huge this hulking battleship is.
Eggman's hologram then appears to greet them, spending some time bantering with Sonic while shrugging off Shadow's threats.
Eggman lays out the groundwork of his latest plan. First, he sets off laser cannons to lock the heroes into his ship without escape.
Two, he cuts off both Tails and Riku's attempts to shut off the lasers by pointing out that he's housing a nuclear reactor in the ship. If they try to mess with his lasers in any way, the reactor will explode, or the battleship will split in half and crash into the land below, causing untold damage to the world.
Third, he splits the groups up, sending Shadow underground while Riku is told to fly off to a nearby building to face one of his machines. This leaves Sonic and Tails behind to face an old friend.
Knuckles appears by punching the Tornado to pieces, then stepping up before Sonic and declaring that he's grabbed the Chaos and Master Emeralds to take over the world.
Tails is angry that Knuckles destroyed his ship even when mind controlled, and prepares to kick the echidna's butt.
Sonic's just not surprised that Knuckles was easily captured.
Meanwhile, Eggman's working on his greatest creation ever and tosses out orders to someone over the intercom. All the while, Orbot and Cubot are trying (and failing) to wrap up another machine before Sonic can get closer.
Back with Sonic, him and Tails try to get Knuckles' attention but the Echidna's having none of it. Even if he wasn't being controlled he'd still act like this, probably.
Sonic and Tails work together to get around Knuckles' incredible strength without hurting him too bad. Just enough to wake him up.
Once he's freed from the Hyper-go-on energy, he recollects his last memories to his friends. Tails hypothesizes that maybe Eggman swiped up Knuckles so there'd be no one guarding the Master Emerald, but thinks that the doctor would be going too far in that case.
Before they can work out Eggman's plans, the doctor's hologram reappears just to taunt them before dumping them down separate pits.
Riku heads to Eggman's Egg Museum, dedicated to the many machines he's made throughout his stunning career.
Riku rolls his eyes and strolls through at a leisurely pace while communicating with Takashi via thoughts. Takashi thinks this is a waste of time and Sonic seems more than capable of handling this on his own.
Riku knows from experience that can't always be the case, and tells him they're staying until they're POSITIVE that nothing's up.
But right after thinking that Riku runs into a display for the Egg Wyvern...Which shouldn't exist in this timeline.
Riku rightfully calls it a time anomaly and now even Takashi is taking an interest in this world. Suddenly Eggman's voice blares over the intercom, deducing that not only is Riku not from this world, but also that he knows a lot about this world already...Including the anomaly regarding the Egg Wyvern.
Riku shivers a bit and Eggman lets out a jolly laugh. He extends an offer to Riku to join the Eggman Empire, but Riku bluntly declines.
Eggman then sics the Death Egg Robot on him as a test of his strength. Riku cuts it in half without using a single element, saying he plans to stop Eggman from conquering the world.
Eggman eggs him onward, saying if he wants a challenge, one awaits up ahead.
Shadow traverses the dank depths of the Egg Continent alone, venting his frustrations on the speakers he crosses along the way.
He is eventually lured into a hexagon shaped room, where Eggman brings out Rogue and Omega to challenge him.
Shadow drops the pleasantries with Eggman and declares he'll die for this one.
Rogue fully believes Shadow has succumbed to his nature as a Black Arms' soldier, while Omega is forced to act a fully loyal member of the Eggman Empire.
Shadow grits his fists and tearfully fights his allies, forcing himself to hold back as much as physically possible to not hurt them greatly.
He first breaks Rogue's mind control and then goes after Omega, getting into a very difficult fight thanks to the machine's unending firepower.
But eventually he knocks his corrupted circuits loose. He then destroys one last speaker to shut Eggman up, and makes sure his comrades are ok.
Rogue gets up first and is a little woozy, but DOES remember what happened before she was knocked out. She had been tasked to infiltrate Eggman's facility and had trailed Orbot and Cubot, but then was attacked by an unknown assailant.
Shadow was investigating on his own outside of G.U.N.'s orders, suspecting Eggman had returned.
Omega then reboots and stands up. His memories of the last twenty-four hours are wiped, but that just frees up more room to hate Eggman.
Shadow calls this the reunion of Team Dark and declares that they'll be going straight after Eggman to make him pay. Rogue and Omega are hardly about to disagree. Thus they rush on ahead, deeper into the Egg Continent.
Team Sonic, meanwhile, survives Eggman's trap by Triangle Diving onto a lone platform, which begins to carry them on a preset path.
Sonic banters with Eggman, who disappoints them by revealing he didn't have the budget for Egg Pawns this time.
Sonic is so disappointed that he decides to nap until they get to their destination, since they really have no choice in the matter.
But soon after the platform splits in half and starts going much, MUCH faster in different directions. Knuckles is forced down his own path while Tails and Sonic go elsewhere.
Eggman is a little worried about how things are proceeding so far and prepares to send Metal Sonic out to intercept Shadow, while Orbot and Cubot deploy the machine against Riku.
Sonic and Tails land back on top and after shaking off a bit of dizziness find their next opponents waiting for them...Amy and Cream.
Sonic fights Amy while Tails fights Cream, both reluctant to go all-out even if the girls aren't giving them the same mercy.
Even with all of Tails' on the fly inventions, its hard to stand up to the power of a pissed off Chao. But once he knocks out Cheese its easy to do the same to Cream.
Sonic then knocks out Amy in short order.
Sonic's starting to get a little annoyed at how far Eggman is taking things now, with Tails lamenting that this is absolutely not the end of it.
They decide to leave Amy and Cream behind since they can handle themselves just fine here, and go on to hunt down Eggman.
Sure enough, the two girls wake up and after recollecting themselves, Amy flares up in anger at how Eggman used her to try and hurt Sonic.
She swings her hammer up and rallies Cream to go after Eggman.
Knuckles, now alone, has to rely on his instincts to beat Eggman's maze and find a point closer to where Sonic and Tails might be.
But along the way, he's pitted against the Chaotix, all three of them.
Knuckles relishes the chance to fight them and manages to win solo, just barely.
Once Vector's back up on his feet the two catch up on what's going on. Vector then offers to fling Knuckles up higher so he can catch up to Sonic.
But once he's gone, Espio points out how Vector hid information on Eggman's secret partner.
Vector says it was on purpose because they don't know if they're dealing with a second Metal Sonic hijacking or not. Besides, G.U.N. told them not to say anything or their pay would be halved.
Once Charmy wakes up, Team Chaotix prepare to help out the others in taking down Eggman, sort of like old times.
Team Dark heads deep into an underground lava sector of the battleship, dealing with some of the traps along the way.
They start exchanging more information and start to understand that Eggman is working with someone else. Rogue tries to get in contact with G.U.N., but can't manage a signal this far down.
She's worried that G.U.N. will try launching a desperate attack on the Egg Continent, so they need to hurry up and disable the nuclear reactor.
After exiting the lava sector they head into a darker laboratory. Omega's scanners detect organic material "not from this world" and one flick of the lights later reveals that Eggman has a bunch of capsules containing incomplete clones of Black Arms soldiers...and Black Doom himself.
Shadow quietly shows his anger and alongside Omega, tear apart the room while Rogue finds them a way out.
They are finally back outside the ship and, right on cue, the laser shields go down. G.U.N. Beetles and Mechs start swarming the area, but don't appear to be going towards Eggman's tower.
They are about to call the G.U.N. Commander when all of a sudden they are ambushed by Metal Sonic, who quietly absorbs the material around him to transform into a new variation of Metal Madness.
The Chaotix then drop by to offer their aid. Thus, both teams prepare to eliminate Metal Sonic from the picture.
A short scuffle occurs before one of Omega's hardest attacks knocks some bolts loose from Metal Sonic's head...including the inhibitor bolt that was still keeping him loyal to Eggman.
Immediately upon being freed Metal Sonic relishes the moment and then stabs himself with the tubes to the nuclear reactor to power-up. Though nothing compared to the God of Destruction, Chaos, this'll suffice in eliminating these six nuisances.
Shadow holds off Metal Sonic's Chaos Control while Omega and Vector hit him hard and the rest quickly strike around Metal Sonic's joints.
Metal Sonic refuses to go down easily, and Shadow suspects they can't win without the Chaos Emeralds...Unless they go for one crazy gambit.
The Chaotix run interference with a Team Blast to fry Metal Sonic's audio receptors while Omega, deafening his sensors ahead of time to avoid the badly played music, fires missiles into the nuclear tubes.
The resulting explosion recoils inside of Metal Sonic and causes him to break apart and collapse upon the ground, defeated.
With victory assured, the two teams decide to split back up. The Chaotix will go disable the reactor, since Eggman's no doubt getting impatient. Shadow will go after Eggman, while Rogue and Omega disable the communications jammer before G.U.N. makes a mistake.
But before he heads out, Shadow decides to haul away Metal Sonic's body to check on something that got his attention...
Catching back up with Riku a few minutes ago, he's managed to escape Eggman's dumb museum and found his way to the barrier controls by accident. He shuts them down, only for the walls around him to collapse and leave him wide-open in front of the eyes of a bunch of G.U.N. Mechs.
They are being led by the ARK-Diablon, a fully bipedal version of the Diablon, being controlled remotely by the G.U.N. Commander.
The G.U.N. Commander assumes Riku to be Eggman's ally based on Rogue's information prior to being cut off.
Riku denies the accusation but is forced to draw his sword anyways to stop the G.U.N. Commander's determination to keep Eggman from further sullying Maria's family name.
Though the ARK-Diablon boasts plenty of tricks that would definitely have given Eggman trouble, Riku's own brand of tricks manages to disable the machine safely.
As the machine falls Eggman laughs happily and sicks another machine on Riku, having figured out most of his tricks from his few short battles.
This newest creation is Mecha Dark Gaia, a machine replica of Dark Gaia piloted by Orbot and Cubot.
Riku won't fight this battle alone, however. Team Sonic has reunited and joins Riku to combat this machine.
The G.U.N. Commander entrusts the fight to them, and shuts down the ARK-Diablon for now.
Mecha Dark Gaia has about as much strength as the real deal, since its running off the last reserves of Gaia Energy Eggman siphoned out of him a while ago.
Sonic suggests going Super, casually bringing out the Chaos Emeralds, but to Knuckles' disbelief.
But with Mecha Dark Gaia sweeping over the battlefield with deadly attacks, it'll be hard for Sonic to concentrate.
So Riku decides to run interference to buy the three some time. Once enough time has passed, Sonic goes Super and surrounds Tails and Knuckles in chaos energy bubbles so they can help out.
Riku then goes Light Form to counter the Dark Gaia energy. All four of them combined are able to turn the tide against Mecha Dark Gaia and destroy it.
Sonic rescues Orbot and Cubot from the rubble, deciding to spare them since frankly, they aren't that bad for Eggman robots.
Sonic sees no more obstacles standing in their way between them and Eggman, thus, the four of them speed off to hit the back end of the Egg Continent...The Final Fortress.
Meanwhile, Shadow has pulled Metal Sonic aside and figured out how to call upon his old security footage. There he discovers the truth of what's going on.
Modern Eggman and Classic Eggman are talking about Modern Eggman's newest plan to turn Sonic's friends against him so he can't rely on the power of friendship to win.
But Modern Eggman also has another plan up his sleeve just in case that fails. And to that end, he'll need the power of Dark Gaia, Hyper-go-on, and Chaos Emerald negative energy.
Shadow suspects Classic Eggman is the ally, but as the video footage continues its clear that Classic Eggman was sent back to his dimension. But Modern Eggman's ally is a familiar face to him and Shadow both...
Team Sonic and Riku infiltrate the Final Fortress and eventually catch up with Shadow at the end. Shadow's about to reveal the truth when all of a sudden, Eggman appears on a giant monitor, boasting his victory.
And around that time, Tails catches...Eggman? flying towards Angel Island in his Egg Mobile.
Shadow reveals the Eggman on the monitor's true identity as Eggman Nega.
Eggman Nega had freed himself from the Ifrit Dimension a while back and happened to run into Modern and Classic Eggman in the White Void. After freeing them, Nega and his grandfather decide to team up again to destroy Sonic for good.
So all this time Nega's been the face taunting the heroes while his grandfather puts their final plan to work.
But as Sonic points out, both Eggmen are running out of tricks to slow him down.
That's not entirely true, as the moment Riku tries to go after Eggman he's thrown aside by telekinetic energy...From Silver.
And not only that, Blaze the Cat has been forced under Eggman Nega's control.
Eggman Nega activates mechanical claws on the side of the platform to grab and toss Tails and Knuckles aside, then sics his controlled nemesis' upon the remaining three.
Sonic and Shadow go Super and Riku activates Light Form. Blaze activates the Sol Emeralds to go Blazing while Silver surprises the group by going Super himself.
Before Eggman can be caught up to, Sonic, Shadow and Riku are going to need to win their toughest battle yet against old friends.
Riku goes after Blaze with Sonic while Shadow handles Silver, being the sole one capable of working around his telekinetic powers easily.
They swap their battle partners frequently throughout and have a thoroughly tough fight by the end of it, nearly throwing all three of them into a state of exhaustion.
Silver is the first to fall to Riku, who forced himself not to use his sword. Then Shadow and Sonic manages to kick up a powerful wind that knocks Blaze unconscious.
Eggman Nega gets very pissed off and plans to eradicate the entire battleship with an orbital laser bombardment he had up his sleeve, stating he doesn't care for his own life as he'll always able to be born again in the future.
But his plans go south when the rest of Sonic's friends arrive as back-up and reveal that they disabled the nuclear reactor and the orbital laser commands present in the communications towers.
Now Eggman Nega goes completely insane and activates the tower behind this arena, turning it into a frightening, unhinged mech called the Egg Imperial Tower.
Amy nudges Sonic to go after Eggman and leave this to them. Sonic thanks her for the back-up and then gathers up next to Tails, Knuckles, Shadow and Riku so Shadow can take them to Angel Island with Chaos Control.
Blaze and Silver then get up to rejoin the fight, peeved at Nega's deception.
Upon arriving at Angel Island they find Eggman perfectly content to just float there waiting for them. He's not touched the Master Emerald, much to Knuckles' surprise.
Tails is quick to point out how the Master Emerald HAS no negative energy to draw out.
Eggman declares his true goal here: Thanks to that hole the "dark child" made a while back, he discovered the entrance to a secret mine hidden deep within Angel Island.
Inside hides a plethora of gem walls that the Chaos Emeralds were carved out of, all filled with negative Chaos Energy.
He plans to harvest the energy there to finish his ultimate weapon, but he just needs to stall the heroes a little while longer.
When Sonic rushes Eggman he's suddenly ambushed by Chaos 0, now under Eggman's control.
Chaos 0 drains the energy from Sonic's Chaos Emeralds and then leaps off Angel Island, plummeting into the water, only to emerge all the way back up as Perfect Chaos.
Sonic and Shadow go Super to pacify Chaos while Knuckles goes to the Master Emerald to subdue him too.
Meanwhile, however, Riku breaks off to follow Eggman into the mine. Along the way he learns about the "dark child" from Takashi, though thinks he's not worth worrying about.
He crosses Eggman about to cross the magma river into the mines. Eggman's disappointed at the lack of Sonic, but figures he can use Riku as a test run for his newest, greatest creation.
Riku thinks Eggman's underestimating him. Eggman disagrees.
With a snap of Eggman's fingers, a bunch of parts from old machines start to appear out of time rifts, merging together into a surprisingly coherent machine called the Egg Chimera.
Eggman boards this machine and prepares to finish Riku off.
The fight is barely able to keep going within this tight corridor, so Eggman activates a function within the Egg Chimera that starts warping them through different battle arenas and points in time.
Riku advances to Dark Form to pierce through the Egg Chimera's Hyper-go-on and Dark Gaia energy barrier, cutting down the Egg Emperor segments at that arena and then dealing with the Big Arms at the Doomsday Zone.
He then tackles the Egg Viper portion at the Final Egg and confronts the Egg Wyvern portions at the falling Egg Carrier of the timeline that shouldn't be.
Eggman confronts Riku about how he shouldn't remember these events, but apparently, it was easy for him to do so given his intelligence combined with being at the epicenter of the reset.
Riku then decides to go into Chaos Form and finishes off the Egg Wyvern portion of the Chimera.
Eggman is shocked by the sudden boost in strength but refuses to bow to Riku. He frees the Time Eater's claws from the confines of his machine and tears open a hole to a new arena.
Eggman starts utilizing the Time Eater's powers to slow Riku down and gain somewhat of an advantage over him. He then pulls out the Egg Dragoon's drills and lasers to slow Riku down further.
When Riku destroys the Egg Dragoon that puts an end to the main body of the Egg Chimera. But Eggman somehow managed to store the Time Eater within and continues the fight within the time rift between dimensions.
But Riku manages to finish off the Time Eater, leaving only the Nega Wisp Armor, which has damaged from all the roughhousing so far. Eggman scrambles to the armor's cockpit and rides one last time rift back to the present in desperation.
Riku pursues and delivers a deadly slash to the back of the machine, causing it to go haywire as it hurtles Eggman all the way to the end of the mine.
By the time Riku catches up the doctor, Sonic, Shadow, Tails and Knuckles are right behind him.
Rightfully calling out his failure, Sonic is prepared to wrap this adventure up when Eggman pulls himself from the rubble of defeat and grin.
Every resource, every second, has been leading to this moment. He has Sonic RIGHT where he wants him. He pulls out a single golden ring from his pockets, and raises it high, activating the gem walls of Chaos Energy behind him.
Sonic cracks jokes but Eggman's clearly sincere in what he's doing.
Eggman takes advantage of this momentary cockiness to infuse the ring with the negative Chaos Energy from the wall.
Riku senses something similar to Sonic and Shadow's Super forms...Only much more ominous.
A red hedgehog is reborn from the ring...A hedgehog that goes by the name of Nazo.
Nazo grins at the opportunity to get revenge on the ones who bested him and even cheekily thanks Eggman for managing to revive him.
Eggman demands Nazo kill Sonic and Shadow immediately, but Nazo doesn't care for the two halves. He wants the whole.
Eggman demands their death NOW, and Nazo just laughs him off as a pest. Eggman then turns on a huge blast of Nega Hyper-go-on energy to try and control Nazo, only for the machines to break.
Nazo is humored, surprised that a mere human would try and control a being of pure power. He makes good on a former promise to show Eggman power by blasting him out of Angel Island and back onto the Egg Continent. He only shows mercy out of an iota of respect for the doctor's deadly ambitions.
He then turns to Sonic and Shadow and tells them how excited he is to be back at the place of his birth, the origin point of the Chaos Emeralds.
But instead of getting into his backstory, Nazo demands Sonic and Shadow become Shadic so he can take his revenge properly.
Sonic tells Riku to back off as this is too much for him, and tasks him with protecting Tails and Knuckles.
Riku agrees in the moment, wanting to figure out what Nazo is capable of.
Sonic and Shadow then use Chaos Control to merge into Shadic, taking the fight outside of Angel Island.
Back on the Egg Continent, Sonic's friends have taken down the Egg Imperial Tower and put Eggman Nega at their mercy.
But then Eggman comes crashing onto the ship, babbling how they're all doomed.
Eggman's prodded by Silver for answers, forcing him to reveal that he revived Nazo, much to the horror of everyone BUT Silver and Blaze.
Even Eggman Nega calls him insane for doing this, but their inevitable bickering is ended by Silver wanting to know who Nazo is.
After explaining him to the others, Eggman curses Riku out for ruining his chances of putting Nazo under his control.
Back at the battle, Shadic and Nazo are clashing at speeds barely recognizable by even Riku's eyes.
But its painfully obvious to Nazo that Shadic came into this battle with very few rings to keep this form going, and laughs at how short this rematch shall be.
But Shadic smirks, stating how he doesn't need anymore than seven rings in hand to take Nazo down.
In the meantime, Riku converses with Tails and Knuckles about having a back-up plan to seal Nazo away again in the Master Emerald if Shadic can't cut it.
Knuckles bluntly points out that the secret to sealing Nazo away is lost forever.
Takashi interjects and offers an alternative solution to Riku...Make a chain similar to the one that bound him and Sodenko to the dark prison, and wrap it around Nazo.
Its not a BAD plan per se, but it all relies on Shadic wearing Nazo down enough to seal him away.
Nazo laughs at Shadic's claim, but its not an empty boast on the fused hedgehog's part.
Sonic, as it turns out, had been keeping the World Rings on him in secret, and now draws on all their powers to transform into Darkspine Shadic.
Shadic uses the powers of Time Break and Speed Break to completely overwhelm Nazo, nearly busting a hole through his gut in the process.
But in the midst of the battle Nazo crashes near the wreckage of the Nega Wisp Armor and grins. He may not be able to draw upon the energy of the World Rings, but the Nega Hyper-go-on energy, on the other hand...
He fuses that and the Dark Gaia energy into his body, emerging as Perfect Nega Nazo, gaining features from the Void Wisp and Dark Gaia himself.
Now the situation is getting out of hand and Riku decides he can't stand idly by. So he joins Shadic in battle in his Chaos Form.
Back on the Egg Continent, Eggman worries that they will not survive this event. Nega rightfully calls him out for making the strongest creature in the universe EVEN stronger.
Silver interjects, however, pointing out that given the linear nature of time travel in their world the fact that he and Nega still exist must mean Nazo won't win this day.
And thus, he suspects that Eggman has one more back-up plan in case of Nazo's disobedience.
Turns out the Egg Continent is armed with a Hyper-go-on vacuum to suck up the Nega energy from Nazo.
Omega and Silver are tasked with fixing the communications array so the others can sheer Shadic on, while both Eggmen go to activate the vacuum, which will take ten minutes total...
Meanwhile Nazo starts using the Hyper-go-on energies within him to turn the tide on Shadic and fluster Riku.
Even Riku thinks Nazo is way too strong to make sense at this point.
Shadic feels like he's running out of energy and so, fueled by the cheers of his friends, he fuses the Seven World Rings together and launches one final flame attack upon Nazo in hopes of finishing him off.
With their fusion burning out, Sonic and Shadow plummet towards the water.
Nazo isn't dead, but his regeneration is barely keeping him together. Enraged, he tries to finish the two halves off once and for all. But then Riku gets in his way, surprising the manic power-mad hedgehog.
Using dark rifts to carry the hedgehogs to safety, Riku pulls back and then calls forth Takashi for back up. Though he doesn't have much faith in their ability to wing, Riku commands Takashi to go at Nazo with no restraints at all for the sake of this world.
Nazo immediately targets Takashi first and wails on him with surprising ease. Riku was hoping seeing this would motivate Sodenko to show regrets for her actions, but she remains stoic to her brother's pain.
Riku then clicks his tongue and forces Takashi to withdraw before he gets killed for nothing, standing alone against the ultimate hedgehog.
Nazo is intrigued by Riku's strength and seems to want to fight more like him, but Riku remains silent and just faces him with a solid grip on his katana.
Even with his body suffering bruising and bleeding, Riku holds his sword tight and keeps striking Nazo as hard as he can.
Nazo hoists him up by the neck and prepares to end this little charade, but its over.
Riku managed to stall long enough for Eggman to activate the vacuum and drain Nazo of the Hyper-go-on power.
Nazo, now weakened, is stabbed through the back by Riku and chained up. Riku then thrusts him into the dark prison so he may never trouble anyone again.
But in the aftermath of this battle, he'll only feel comfortable knowing that Eggman will never be able to do this type of stunt again...
Riku confronts Eggman and Nega in the control room for the vacuum. Sure enough, Eggman was planning on taking the energy mixture with him for use in futures plans.
Riku destroys it and then threatens Eggman. Eggman points out that Riku doesn't have it in him to kill him.
Riku agrees, stating how Eggman is a necessity in the world, like it or not. But the 11 people on their way here might have other ideas on what to do with him...
Eggman gulps and tries to bargain his way out of here, even offering up his grandson as a hostage, much to Nega's displeasure.
Riku accepts, and Nega is captured while Eggman flies to freedom.
The heroes then show up and Silver and Blaze take Eggman Nega for themselves.
Now all that's left is to get rid of the Egg Continent. Takashi is able to handle that, using his immense strength to slowly push the hulking battleship through a rift towards the sun.
While he takes some time doing that, Sonic and Riku finally have their race.
During the race Sonic realizes that Sonic had let Eggman go on purpose but doesn't mind. He likes having fun with old Egghead, since things always tend to work out in the end.
Sonic winds up winning the race pretty handily, but Riku's fine with that.
He's enjoyed his time on this world for however short it was, and after bidding Sonic farewell, Riku leaves to go save other worlds.
Meanwhile, Eggman licks his wounds at an old base with Orbot and Cubot at his side. Apparently Metal Sonic's gone AWOL, but Eggman figures they can salvage him later.
He has other plans to worry about, including something regarding a "LOST HEX". But as he withdraws those plans from his drawers, he tanks a glance into the darkness...
There he finds glass tubes containing incomplete copies of Chaos, Black Doom, Dark Gaia, Ifrit and Iblis...Stating they'll be a plan for another day.
Part 4 Story 4 END.
Part 4 Extra Chapter 1 (The Other Overlord):
Upon leaving Sonic's world behind Riku attempts to go searching for another world to help out, only to come under fire from a burning meteor.
He lands on a nearby asteroid where he sensed the energy come from and is greeted by a dramatic lightshow and terrifyingly shrill laughter from a somewhat familiar face.
He is greeted by Overlord Laharl, Etna and Flonne from the Disgaea series. Laharal, as per tradition at this point, is attacking Riku because 1) His series was denied a story in Part 4 and 2) So he can steal Riku's main character title from him.
Riku is completely dumbfounded by this but sees that there's no avoiding a battle with the trio. Laharl, however, forces Riku to play by Disgaea rules, grid based combat and all.
Riku accepts, and their battlefield transitions.
Riku's lower leveled than all three of them, and it doesn't take long for Flonne and Etna to chip away at his health with their special moves.
However, Riku's able to stall out Laharl's attack by pointing out that surely the person who lands the final blow on him would get the "main character" title.
Etna smirks and plans to snipe the final blow herself. But as the opportunity presents itself, Riku manages to survive through his Evility, which leaves him with one HP.
This gives him a chance to go into Chaos Form, boosting his level to a staggering 9999+, which Laharl totally calls cheating.
Flonne transforms into Pure Flonne and actually manages to deal a hefty chunk of damage to Riku's HP with her strongest attack. But then Riku activates his counter move to finish her off in one strike.
Etna tries to summon a ton of Prinnies to suicide bomb Riku but, seeing Riku's insane stats, decide to blow themselves up on Etna to spite her.
Riku then takes Etna out in one attack and positions himself to defeat Laharl too.
Laharl, refusing to stand down, activates HIS transformation...Which turns out to be painting his hair in irradiated yellow paint and doing a bad photoshop job on all his stats.
Riku rightfully calls him out on this shameful behavior and Laharl, in a brief lapse of self-awareness, realizes he's actually acting like a total moron.
Riku then finishes him off and the battle's over.
Laharl's pissed, but Riku manages to talk him down by playing to his ego a little, pointing out that despite how little he's been the main character, he's still managed to endear himself to so many players and continues to make appearances even to this day.
Laharl feels satisfied with this answer for now, and decides to leave Riku be. Turns out, as Etna reads Riku's stats, that he doesn't even have a "main character" title to steal anyways. Just some dumb "Phoenix of Balance" title.
The trio leave, bickering all the way. Riku then scratches the side of his head, seemingly tainted by the group's meta humor for a brief moment...