Sonic was in the Chemical Plant, looking for Doctor Eggman's computer in one of his bases. He found the computer, and accessed the files he needed, before getting an SOS call from Amy.
"Sonic! Infinite and his army are here! They destroyed home base, and are killing our team! You need to hurry here, NOW!"
"Don't worry Amy! I'm on my way, be there as quick as I can!" Sonic then blasted off into a run, and was about to get out of the Chemical Plant, before a foe blocks his path.
It's Shadow. His eyes are full of fakeness. And that's not an insult.
"Shadow! Is it really you?" Shadow didn't say a word, but just shot a Chaos Spear at Sonic. Sonic dodged it.
"Yeah, I figured as much." Sonic then dashed towards Shadow and threw a few quick punches. Left, right, left, kick. Shadow took a few hits, but grabbed Sonic's foot as Sonic attempted to kick him, then threw him off the platform, and walked away, assuming Sonic's death. However, Sonic grabbed the edge before he fell, and when Shadow started walking away, he got up, he ran, and slid under his feet, making Shadow get launched a bit upwards, and then Sonic did a powerful kick while Shadow was in the air, and launched him off. Sonic could see Shadow turn into Ruby pixels as he fell.
"Now enough of that. The resistance needs my help!" Sonic then ran to the city to see utter destruction. Right as he entered the city, he witnessed three robots shooting at a single soldier, with a cube hammer. As the soldier tried to swing, a robot knocked the hammer out of his hands, and pushed him to the ground. The three aimed their guns at him, ready to shoot, before Sonic destroyed them with homing attacks.
"S-Sonic! Thanks! The city needs you!"
"You need to get out of here, find a base in Green Hill, I'll take care of this!" Sonic then ran off, and looked up at a Death Egg Robot. It looked down, and was about to step on Sonic. Luckily he rolled at the last second before it crushed him. He then saw Infinite in the town square, who had just thrown Gadget to his imminent doom. He was about to go and save him, but then got grabbed by Chaos, who threw him into a building, breaking him through the wall. Sonic groaned in the rubble.
"Ugh... G-Gadget! Out of the way... Chaos...!" He slowly got up, and boosted at supersonic speeds towards Chaos, turning him into rain. As Sonic was about to turn the corner to see if Gadget was okay, 14 robots, had their guns pointed at him, and they shot. Sonic took a few hits, but then jumped back around the corner, picking up a couple scattered rings.
The robots slowly stepped closer, and were about to finish off Sonic, before they suddenly turned blue. Silver jumped in and smashed them all against a building, destroying them.
"You okay, Sonic?"
"Silver! Thanks for the save, but Gadget and the others need my help!" Right as that's said, buzz bombers fly in, and shoot at both of them. Sonic runs up a building, and backflips off of it, kicking one in the face, and silver shoots a couple psychic knives. Sonic runs past the corner, but he's too late. His eyes widen as he sees Gadget and Classic Sonic's bodies, and Tails and Fuchsia being dragged away by mechs.
"SONIC!" Tails screamed kicking. Sonic rushed over, but then got dosed with cubes, making him see spikes, and Silver looked confused as well. Sonic dodged a bunch of spike walls, and lasers being shot at him in the nightmare, and when he came too, Infinite was in front of him.
"Welcome to the party, hedgehog. A bit late, but I suppose it's better than nothing." Sonic tried to run past him, but Infinite could keep up with his speed, and stopped him, and only gave him the choice to watch his friends get dragged away.
"Gadget... What did you do to Gadget and the other Sonic?!"
"No worries... Gadget is merely temporarily paralyzed, and knocked out. The tic-tac however... He didn't suffer for long, if it makes you feel better." Sonic clenched his fists, and swung at him, and Infinite dodged his every move, and kicked him into a building, cracking his back pretty hard. He groaned in pain, as he fell on his side.
"This is it for the resistance. Everything you worked up for, and everything you fought for... Was it worth it?" Sonic tried to get up, but couldn't. Infinite grabbed him by the neck, and Sonic was barely moving.
"You fought well, hedgehog. I admire your strength and confidence. But it wasn't enough. Goodbye." Infinite started choking him, and that's when Sonic kicked Infinite in the gut, causing him to drop Sonic, then he did a spin kick, and knocked Infinite on the ground. He dashed to his friends who were about to be put in capsules, and kicks down a robot, and boosts through the rest. Tails, Fuchsia, other resistance members, and the bodies of Gadget and Classic Sonic were dropped and freed.
"Thank you, Sonic... But... We lost the other Sonic..." Tails said, sadness in his voice.
"And Gadget..." Fuchsia started, but never finished.
"Don't worry Fuchsia, Gadget will wake up soon... But... Infinite was just... so brutal..."
"He's a monster, Tails... We have to stop him."
"Hmhmhmhm... You? Stop me? How absurd." Infinite said, floating over. Fuchsia slowly picked up a laser pistol, and aimed it at Infinite.
"You're gonna wish you never came to this town!" Fuchsia exclaimed, shooting at Infinite. He dodged without issue, and shot a laser beam from his hand, driving it slowly across the ground near her, before turning the laser on the unconscious Gadget.
"And you're gonna wish you died." Infinite said about to execute Gadget, before Tails threw ring bombs at him, doing a bit of damage.
"Agh! Why you little..." Infinite turned and charged at Tails, and gutting him with the hallucination claw, Tails starting to see nightmarish things, and freaks out.
"Tails!" Sonic said, rushing over to Infinite, and kicking him in the back of the head, before trying to snap Tails out of it.
"Fool." Infinite just stabbed Sonic with the same claw having him see things as well. He saw robots with spike shooters, and they shot at him. He dodged, but got hit with one, causing him to fall one knee, and snapping out of it, and looking up to Infinite standing over him, charging his laser beam right at his head.
"Die for me, would you?"
