A/N: Special thanks to ReaderWriterLoner, who made this possible, this story is finally published. Basically this is something like OC Survival on the Killing Floor, only with a totally different plot. Note that you can add up to 5 characters, but I recommend little submission because if there are too many characters, I'm gonna have to separate them. I don't want to make this look like a big war. Submission format is like OC KF, but without perks. Look at my profile. I know that it's supposed to be in Xovers, but I'll change it soon, if I need to that is. Some stories aren't in crossover section although they ARE crossovers aren't they?

Me – Levinski.

ReaderWriterLoner – Mike.

Shadow's Party Girl – Chelsey, Starlight.

Anything170 – Don, Ghost, Cole.

SEGA(Sonic The Hedgehog character) – Tails, Cosmo.

Disclaimer: I don't own, Sonic the Hedgehog, Left 4 Dead, or any characters I don't own.

Chapter 1 : Infection

"HEY! HEY, OVER HERE!" yelled a grass green fox on the rooftops while waving his hands at a chopper. The aircraft couldn't hear his voice though, so it didn't even turn around.

"HEY! TURN BACK! WE'RE STILL ALIVE DOWN HERE!" yelled the fox again, "HEY! COME BACK!"

"It's no use, Levinski." said a blood red wolf to him, "They're not going to hear our voice..."

"Yeah, just waste of your strength, bro" said a blond twin-tailed fox, who had similar appearances as the grass green fox.
Levinski turned back at his friends, scratching his bangs. Aside from the last 2 Mobians, there was a white wolf who looked just like the blood red one. Next to him was an older-looking dark blue wolf, somewhat bearing resemblance of the white and blood red wolf.

Sitting on a nearby table was a purple feline with red highlight and long tail with fluff at the end, who was brushing her dirty skirt. Standing next to her was a pink hedgehog with bangs parted slightly, quills went to her midback. She was looking down on the streets, but with fog and smoke coming from the building, it's really hard to see anything.

There was also a green seedrian among the group. Her eyes were looking worriedly at the door. Sounds of growls and moans could be heard from there.

"Any luck?" a tall brown skinny hedgehog approached the group. Levinski turned to him and answered.

"Nyet, Mike. Could've gone worse, though."

"Well, what should we do now? Going down there?"

"Looks like our only option. Don has suggested that" Levinski turned to the blood red wolf.

"What about the others? Have they agreed yet? From the looks of Cosmo, I think she'll disagree."

"Well, she'd be more scared when we get cornered here. I think Chelsey has agreed."

"Just because she's looking down at the street doesn't mean she wants to go down there, Lev."

"Well, Starlight agrees."

"That's obvious, Annie. Your feline girlfriend doesn't want you getting torn apart, or dropped off from the building."

"Don't. Call. Me. Annie. And what other choice do we have? The sooner we get out from this building, the better."

Don approached both the hedgehog and fox. "Hey. You done arguing? The others have been waiting to go down. I mean, look at Ghost. He's already loading his pistols."

The white wolf in question was holding dual Desert Eagles and was leaning against the wall. He looks impatient.

"Where's Cole? He was here a minute ago." Asked Levinski. As if to answer his question, the dark blue wolf arrived, with box full of weapons in hand. It was just minor ones though. There were only USPs, and melees. "Sorry. This is all I could find."

"Better than nothing. Guys!" Levinski called, "Pick up your weapons. We're outta here!"

The group was now going downstairs, all guns are aimed forward. As they were in the corridor, the sight of pale-skinned humans and Mobians were visible. As they saw the group, they began to growl and made a dash toward them. Without even thinking twice, Mike and Cole emptied their clips on them, killing them with one or two shots.

"Zombie fuckers…" muttered Cole under his breath. Suddenly they heard a gurgle just next to them. Levinski was the first to turn around, to see a fat zombie in front of him.

"TAILS! WATCH OUT!" But too late. The zombie vomited on the kitsune, covering him with green, smelly puke. "Ew, what the…?"

"Get off my brother, you bastard!" Levinski shoved the zombie away and quickly thrust his crystal blue machete on its stomach.

KER-SPLAAATT!

The result was unexpected, as the vulpine was soon covered by the same puke covering Tails. "I'm covered with shit!"

"INCOMING!"

Numerous zombies started to pour on the corridor. But to the group's surprise, they only attacked the bile-covered foxes while ignoring the existence of the other Mobians.

Levinski started to growl, before shouting, "RAGING STORM!" Every single zombie nearby was torn apart in a second, freeing both Tails and Levinski. "Phew…" said Tails, "Lev, is… whatever covering us infectious?"

"I don't think so. And the shit has dissolved now. God, I really need a shower now." The group continued their way, this time more alerted. They were, however, unaware of a crawling hooded figure behind them, at least until they heard some doggish growls.

"The hell is that?" said Mike. Just as he turned around, he was pinned down on the floor. The zombie started to tear his flesh apart. "GET-!" Mike wasn't able to finish it as he was continuously being clawed, "GET OFF!" Already had enough, the brown hedgehog held the zombie's hand and rolled over, in turn pinning it down. Mike pulled out his bowie knife and stabbed the zombie on its forehead, killing it instantly.

"You alright, Mike?" asked Chelsey.

"Almost got torn apart, but I'll live."

"And I thought vampires are bulletproof." Said Levinski.

"I don't know. Those claws looked like they can tear apart cars. Let's just get going." They continued walking on the corridors, running into some zombies, only normal ones. "I think this whole madness isn't so bad after all…" said Ghost, "Hey, look! That guy over there might still be alive!"

He was referring to a Mobian in a hazmat suit. No one could know if he was a zombie or not. That is, until he growled and charged toward the group. "HOLY SHIT! That guy was in a freaking hazmat suit for crying out loud!" exclaimed Ghost.

"JUST SHUT YOUR MOUTH AND SHOOT!" Cole shouted. It was rather hard because the zombie's suit was thicker than shirt. It didn't take a while before it went down. "I hate those things…" said Levinski.

"Don't we all?" replied Starlight, "Let's go. The fire's spreading. If we stay here a little longer, we'll either die with our brains eaten, or die with our bodies barbecued." The group went downstairs due to the broken elevator on the top floor. Fires blocked their way further down, so they decided to look for a way down somewhere else. They quickly entered the corridor, only to meet a coughing zombie with mutated mouth. Its tongue shot out from its mouth. It was really long, so that it was able to wrap on one of the survivors on the group, which happened to be Cosmo.

The young Seedrian was dragged all the way toward the zombie. The smell of her flesh must've attracted several other zombies that they began to pour from other rooms.

"COSMO!" shouted Tails panickingly. He had already lost her once, and he wasn't planning to lose her again. He took out his brother's machete and threw it at the tongue, freeing Cosmo. The yellow vulpine dashed toward the zombies and started taking them out with his dual USPs. The zombie with mutated mouth and long tongue was the first to go down. It exploded into smokes as it died. The others were following it. As he was finished, Tails approached Cosmo, checking her.

"You're alright, Cosmo?"

"Little bit slimy, but yes. I'm alright…" Levinski stepped forth and took his machete.

"Next time you want to use my machete, you better ask me first."

"hey, guys! You might wanna take a look at this!" called Mike, holding some kind of document. Don walked toward him and looked at the document. "It looks like some sort of survival guide." He spoke.

"Well, it also contains the type of zombies we've been fighting. Check this out." everyone looked at the document. They saw the hooded zombie, the fat zombie, and also the zombie with long tongue in the document, "the fat guy we ran into was called 'Boomer'. Their bile attracts zombies. when they die, they burst into those biles."

Mike then flipped another page, "The hooded one is called 'Hunter'. Very agile one and can sneak on us. Well, we know how it attacks us. The one with the long tongue is called 'Smoker'. Said to have… multiple tongues that can grow up. We also know how it attacks us." He flipped the page again, "The page is ripped off, but I think I got another one. 'Jockey'. This zombie… rides on you?"

As if the cue, Ghost's scream was heard from behind. "AAAH! THIS THING'S RIDING ON ME! GET OFF ME, I'M A WOLF, NOT A HORSE!" A zombie wearing a white t-shirt and blue boxers was riding on Ghost's back, like a horse. It also controls him like it. Cole was the first to react as he shoved it away in a blink, causing it to collide against the wall, where he finished it off with several shots.

"You okay there, Ghost?"

"My back hurts a bit, but not a biggie."

"Rides on you…" muttered Starlight, "Now I get what it means. If one of those things tries to do that on me, they're sooo gonna regret it."

"Eh, your glares can scare them away before that happens, Star." Joked Levinski.

"Let's just get going. I don't like this place already, with all the zombies and fires." Said Tails.

"Sometimes, I wish I can fly like you, bro."

"Then grow another tail. You're a scientist, I'm sure you know how to do that easily."

"You mean experimenting on myself? Nyet, thanks." The group was quick to find another elevator, a working one. They quickly got in, not wanting to deal with anymore zombies there. "Phew. We're safe." Said Chelsey.

"For now. I guess more are waiting down there." Replied Mike.

"Isn't there something called 'safe room' on the news?" asked Cole.

"Yup, it's a room with red metal doors, preventing any kind of zombies from getting in. Not so safe from infection though."

"I guess it's official," said Levinski, "We're all immune. If we aren't, the infection would've turned me into a zombie already, or at least give me symptoms. I mean, do you experience any? I'm referring to you normal Mobians, not vampires like Mike, Don or Ghost, or someone like you, Cole." Everyone shook their heads.

"I still guess we're damn lucky. But we're not immune to death, so we still have to fight them."

"It's ob-" but Don was cut as the elevator shook hard. Everyone soon knew that the elevator had stopped. But the doors didn't move.

"Jammed. We need to pry it open by force," said Mike, "Hang on, and be ready. The document says zombies are sensitive with sound." The brown hedgehog opened the door with a loud clanging sound. Growls could be heard from outside meaning that the zombies were aware of the survivors.

"Here they come!" said Mike. Just as he said it, all hell broke loose.

A/N: First chapter ends with cliffhanger. But if you ever played the Left 4 Dead 2 Dead Center campaign, you'll know what happens.

Review and/or submit, please!