Back at the Resistance Base...
Tails: I got it, Sonic! I figured out a way to stop Eggman's Phantom Ruby!
Sonic: Great work, Tails!
Tails: Based on these readings, the Phantom Ruby requires an incredible amount of energy, which only the Death Egg can provide. We simply stop the energy transfer, and boom, the Phantom Ruby is practically useless.
Knuckles: Simply? Last I checked the Death Egg is a heavily fortified... well, Death Egg.
Tails: True. But I came up with a plan. First, we distract Eggman. While he's not paying attention, we use the Chemical Plant computer to hack into the Death Egg's weapons systems and shut it down. With no weapons, destroying the Death Egg will be a piece of cake. No Death Egg means the Phantom Ruby is nearly useless.
Knuckles: Well, you know, it's just crazy enough to work. So first we need a distraction. I'm on it!
Amy: No way, Knuckles. You're too easily distracted. That's not a good trait for a distraction.
Knuckles: Hey!
Silver: How about the rookie? Eggman would never expect it. It may even throw him off a little.
Knuckles: Good idea! You've got your orders, rookie. We only have one more day before Eggman's plan is executed, so let's hustle!
Buddy: *to himself* Great, another solo mission. *to Knuckles* I'm on it chief!
Act 16 begins. Buddy runs through Guardian Rock in Green Hill to distract Eggman. It's not an all 2D level anymore. Meanwhile, Sonic is near the Chemical Plant.
Sonic: I'm almost at the Chemical Plant. How's Buddy doing with the distraction?
Knuckles: So far so good. We might have to stop using the nickname "rookie" if the kid keeps this up.
Tails: Next, we've got to get to the computers at the Chemical Plant and shut down the Death Egg's weapons system.
Sonic: Perfect. I've been waiting for my turn to bust some heads!
Act 17, Network Terminal begins and is a mix of Modern Chemical Plant from Gens and Cool Edge from Unleashed. After this stage...
Rouge: The Death Egg's weapon systems are down! Now is your chance! Move!
Tails: Hurry! Just destroy the Death Egg and cut off the Phantom Ruby's power supply!
Vector: You're making it sound like a walk in the park. This is the Death Egg!
Classic Sonic: No sweat, I'll blow up that place and be back faster than you can say sonic speed. That egghead won't know what hit him.
Classic Sonic boards a shuttle with Modern Sonic, Tails, and Knuckles who head to the death egg to blow it up. Act 18, Death Egg Zone begins.
Knuckles: *on communicator* How's it going little Sonic?
Classic Sonic: I'm almost at the reactor now, how are you guys doing?
Knuckles: So far so good, just don't get too cocky and fall.
Tails: Hey, it's Sonic we're talking about.
Sonic: Just keep going little me.
After the level ends...
Classic Sonic: Got it, I'll blow the place and be outta here in a minu- woah! Classic Sonic dodges a blast and brakes near a pit in front of the reactor, powering the Death Egg.
Infinite: Well well well. What do we have here? A miniature hedgehog?
Classic Sonic: Who's this joker?
Tails: *on communicator* Sonic? Is everything ok?
Infinite: You shouldn't be hard to crush. Let's make this quick.
He shines a bright light and before Classic Sonic appears a Death Egg Robot Sentinel.
Classic Sonic: Hehe, I guess some things never change.
Music Insert:
A new Death Egg Robot Boss fight here, very reminiscent of the fight in generations but more difficult.
You must first break through the illusion in order to attack Infinite, who is pulling the strings. The battle ends when Classic Sonic manages to break Infinite's illusion and catch him off guard.
Knuckles: He's down! Blow up the place and outta there!
Classic Sonic nods and runs off into the engine room. After that, the Death Egg is seen suffering numerous explosions around its hull before it is destroyed in a single large explosion. Everyone cheers as they see the Death Egg is destroyed.
Amy: They did it! The Phantom Ruby's power should be down to almost nothing!
Rouge: Mission accomplished. The Phantom Ruby's signal has gotten much weaker.
Shadow: This should effectively put a stop to the doctor's greatest weapon.
Vector: The Sonics have made an opening for us. We can't just let that go to waste.
Silver: This is the moment we've been waiting for. Time to settle the score!
Knuckles: Now that the Phantom Ruby is out of the way, we can finally smash Eggman into an omelet!
Rouge: Hey, don't count your chickens before you smash the eggs!
Sonic: Rouge is right. The fact that Eggman and Infinite are still around means we can't let our guard down.
Knuckles: All right, fine. Everyone get your game face on! The target is Eggman at the Central Tower!
Meanwhile, at Eggman's base in Metropolis, Eggman, Orbot, and Infinite watch the Death Egg's demise on the screen provided by Cubot. Eggman is livid over losing the Death Egg again.
Dr. Eggman: Grr, those resistance pests and their clever little plots. No matter, let them cherish what small victories they think they've had. Only five more hours before the plan is executed. Infinite, let's make a tactical retreat so that we can re-mobilize our forces.
Infinite: And by "tactical retreat" you mean to say, "flee with our tails between our legs." I'm quite displeased about this, Doctor. I had expected more out of the great Doctor Robotnik. Perhaps I was wrong to work for such a weakling.
Dr. Eggman grows angry, and shocks Infinite using the Phantom Ruby, as Infinite groans in pain.
Dr. Eggman: I thought I warned you about your tone, Jackal! Now shut up and follow me. Just because they've blown up the Death Egg doesn't mean they've won this fight yet!
Eggman roars off in the Egg Mobile as Orbot, Cubot, and Infinite fly after him.
Infinite: You will regret that...
???: Worry not, you only need to tolerate the fat fool a little longer.
After that, Act 19, Metropolitan Highway begins. Sonic, Shadow, and Tails confront Eggman, along with Orbot and Cubot, on one of Metropolis' rooftops.
Dr. Eggman: Welcome, Sonic, Shadow. Glad you could make it to your funeral! Infinite?
Infinite: Take this!
He creates a portal, similar to the one he made in episode Shadow.
Sonic: What is that?
As Eggman speaks, Orbot and Cubot realize the severity of the situation and scamper away in the opposite direction in absolute fear.
Dr. Eggman: Har-har. That, my spiky little nemesis, is Null Space.
Sonic: Null Space?
Dr. Eggman: It's a little something I discovered while analyzing the Phantom Ruby; a closed-off space where absolutely nothing exists! One way in, no way out!
Shadow: So that's where Infinite sent me. Don't get too close, Sonic!
Tails: But we destroyed the Phantom Ruby's power source.
Dr. Eggman: Tsk, tsk. Since you ALWAYS destroy the power source of my weapons, I decided to learn from my mistakes. I had a backup power source created under Metropolis. Goodbye, Sonic, my soon-to-be-eradicated nemesis. Enjoy all the nothing!
Eggman rockets the Egg Mobile skyward as Infinite fires another shot before retreating backward to safety. The second shot enlarges the portal and activates a powerful suction vacuum in it, catching Sonic and Tails by surprise by the force of the pull.
Shadow: Everyone get back!
Shadow jumps away as the portal begins sucking everything in. Tails holds onto a building piece while Sonic is losing his footing, unable to resist the pull from the portal. Just as Sonic loses his footing completely and starts to be pulled into the portal, Buddy swings in and grabs Sonic, struggling to hold onto him for as long as he can.
Sonic: Buddy! Don't! You'll be sucked in too!
Buddy's cable breaks, and Sonic and Buddy get sucked into the portal, which promptly closes. Tails is in disbelief over what he just witnessed.
Tails: Sonic! Buddy!
Dr. Eggman: Hahahahaha! You're buddy's not here to save you now!
Infinite looks down. He glares at Tails who begins cowering like before with Chaos. He then sees Shadow and takes off.
Shadow: Get back here Jackal! I'm going after Infinite, you take care of Eggman.
Tails: *is shaking* Sonic...Sonic...I... I can't... I--! *inner monologue* Why am I scared now? I've fought Eggman before and won. I've fought Chaos in his stronger form and won! Why? Why now? Why am I doubting myself? I thought I'd finally grown! Was it not enough? Sonic... I failed him. I failed everyone. I haven't grown at all!
Shadow: TAILS! PULL YOURSELF TOGETHER!
Tails gets frightened by Shadow's tone shift.
Shadow: Sonic is GONE, but do you think he'd want you to fall apart the second he disappeared?! Stop feeling sorry for yourself and get back into the fight!
Tails realize what he's saying, and has a flashback to when Chaos showed up and he hid. He then remembers everything he'd been through with Sonic, specifically his words to him on the ARK.
"I'm counting on you Tails!"
Shadow: Cowards hide. Heroes fight. Make your choice and stand your ground, Fox!
With that, he takes off to chase after Infinite.
Dr. Eggman: Hohoho! Are you going to fight me all on your own, Fox boy?
Tails is scared but finds strength once more, realizing he has to step up.
Tails: He's right...I don't need him to save me. Not this time! This time, I'll save him!
Tails loads up his gear and stares down Eggman.
Tails: Come at me with everything you've got, Eggman!
Tails takes flight and attacks Eggman. A boss fight begins with Tails fighting Eggman in a new mech, closely resembling Big Arm from Sonic 3.
Once Tails defeats Eggman, the doctor retreats, curing the fox. After the fight, Tails drops to one knee, panting and reflecting on all that's happened.
Tails: I did it Sonic... I was scared but... I did it... just like before.
He thinks back to their last few adventures, in which Sonic took the lead and he had taken the back seat, acting as just a navigator or handyman.
Tails: I've been relying on Sonic too much to save the day, just like when I first met him. Sonic's always so confident and rushes headfirst into the fight, no matter the danger... but I hesitated... Maybe... maybe I won't always be brave like you. But even still... I promise I won't back down ever again. I'll remember what you've taught me... and be my own hero.
Continue to the Next Act...