A/N: I'm putting my other stories on hold until I can figure out where to go with them. I may even rewrite some of the worst bits. In the meantime, here is something I have been bouncing about my brainpan for a while.

Genesis, 2558

Cortana's guardian was escaping, Blue Team was sealed in a Cryptum, and Fireteam Osiris was on their last legs. In short, it was SNAFU. 031 Exuberant Witness, however, was relieved. "Cortana is now out of the systems, and I have regained full control of my installation! Thank you, reclaimers."

"Well, I'm glad that someone is happy," Buck snapped.

"Cut the chatter, Osiris! We need to get Blue Team out of the cryptum," Locke interjected.

"Oh, that will be no problem. With my access restored, I can open the Cryptum, and release the other Reclaimers," replied Exuberant, happy to help. "Stand back!" With that, the cheerful monitor floated over to the sphere. A blue beam of light extended from it to the Cryptum. "Just a few more seconds." Finally, the device began to crack open. Osiris could now see the imposing silhouettes of the legendary soldiers. With a light hum, the Cryptum disappeared, dropping the SPARTANs to the floor with a loud thud. They picked themselves up, shaking of the Cryptum's effects. Their recovery was soon interrupted by an uncharacteristically worried Exuberant. "Reclaimers, I seem to have triggered a security system put in place by Cortana. We should most likely leave the area." Before the two teams of SPARTANs could comply, however, a swirling portal engulfed them before disappearing. "Oh, well. I suppose I should check the systems for any other similar devices. Wouldn't want that to happen to the next Reclaimers to arrive."

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The Crystal Labyrinth, outside of time

Somewhere, a Chaos God smiled. He reached out into the Immaterium, or Slipspace, or whatever the mortals called it, and plucked the travelers from it. 'This should be entertaining,' he thought as he shoved them onto another course. 'They will disrupt so many delicate plans.' He rubbed his gnarled hands together with glee. Yes, Tzeentch would enjoy watching this.

00000000

Hong Kong, 2015

A pair of sectoids poked at a gel-covered body, preparing it for transport. Out of the corner of its eye, one of them noticed a flash of blue. It looked curiously in the direction of the flash, but didn't see anything of interest. It gave its race's equivalent of a shrug, and went back to the body. Any thoughts as to what it might have been exited the sectoid's mind, along with several chunks of grey matter as a 7.62mm bullet tore through its skull, reducing the head to pulp. Its partner's head shot up at the noise, but it suffered the same gory fate as Frederick-104 squeezed the trigger of his DMR a second time. Walking up to the corpses, both teams paused. "What the hell were those things?" Vale was the first to speak up.

Locke was quick to respond, "It don't know, but it appears to be responsible for this," he said while gesturing to the unfortunate abductee. "For now, treat all non-human contacts as hostile until we figure out where we are." In response, his team's icons flashed green on his HUD. "Let's keep moving."

"Fuck, fuck, fuck!" Operative Velasquez shouted as he fired an LMG burst into a nearby Thin Man. "Big Sky, this is Strike One-Actual. We need immediate evac NOW! Mills, Osterman, and Ryan are KIA, and I'm not sure how long Zhang can hold on!" Said soldier had taken a plasma bolt to the stomach, and was currently unconscious and mumbling something about a stolen diamond shipment. Mills, their Medic had been the first to die, a lucky plasma shot hitting the gas tank of the car he had been taking cover behind. Osterman, their Assault, had gotten too close to a Thin Man and choked to death on the poison. Ryan had been on a nearby rooftop, when a Floater shot the sniper in her back. The entire mission was FUBAR, and Velasquez was low on ammo. He heard the roar of an approaching Floater. He swung around to bring his gun to bear, only to hear the dreaded click of an empty magazine. "Shit!" he swore as he grabbed a frag grenade and prepared to go out with a bang. Before he could pull the pin, he heard a loud crack, and the alien was blown nearly in half. His head snapped towards the source of the noise, and he dropped the grenade in surprise and awe. Striding towards him were eight of the largest soldiers he had ever seen. The four in front must have been nearly seven feet tall, and were wearing angular, thick-looking plates of armor. The rear four were significantly shorter, only around 6', and their armor looked sleeker and lighter. Despite that, they looked just as lethal as the giants.

Their apparent leader, a titan in battle-scarred olive green spoke with a deep monotone, "Soldier, sitrep."

"Uhhh, Operative Velasquez, XCOM heavy. The one on the ground is Operative Zhang, also a heavy."

"XCOM?"

"The eXtraterrestrial COMbat unit, formed to defend Earth from the alien threat."

"We're on Earth?" the giant said with a tone of disbelief. Behind... Him?... It?, the others shifted and shot each other looks.

One of the smaller soldiers spoke up, "Well, ain't this just great. And I thought I'd had enough of alien invaders for a lifetime."

00000000

So, here is the first chapter of my XCOM:EW/Halo crossover. I'm sorry if you were looking forward to another chapter of one of my other stories, so I promise that I will work on them as soon as I can. Also, while I did include a bit of WH40k, that was just to explain how our heroes traveled. I am not planning on adding any more, as the Ruinous Powers already have a galaxy of their own to mess with. Tzeentch is just doing this for a bit of fun.