What if UNSC replace System Allience from Mass Effect

2552. Humanity is at war with an alien alliance known as 'The Covenant' We are losing. In an attempt to assault the carrier of one of the Covenant's leadership. The carrier jumps into slipspace above New Mombasa. Those whom survive the blast find themselves on a new, dangerous, frozen world.

After a successful mission, a UNSC fleet makes a random slipspace jump only to come across an uncharted system containing a sliver of humanity, one with seemingly no connection to Earth and whose natural abilities defy reason. In a galaxy full of terrifying dangers, the UNSC and Remnant must work together to defend all they know from annihilation.

Reach, el bastión de la humanidad, ha caído. Uno de los Spartans del equipo Noble se quedó atrás para proteger al Pillar of Autumn, El es conocido como el Fantasma Viviente, el Lobo Solitario, la Parca Personal de la ONI... o simplemente, Noble Seis. Ahora, lejos de su hogar y su tiempo, deberá levantarse una vez más. No solo por un planeta. No solo por una especie. Una galaxia.

The Republic after finding a small planet on the edge of their space, is introduced to the Milky Way. For 15 years there was an unstable peace. However War is indeed inevitable and the Republic, after an incident over a Terran Colony, began its invasion. But Terrans do not go quietly. These are the stories of those who fought the war which will be known as... Bellum Terranum.

Throughout countless galaxies, civilizations have warred in the stars, clashing with their warships over endless worlds. Each of these civilizations calls their ships something different, let’s find out what those are.

For the last two thousand years, Themyscira has isolated itself from the rest of mankind. Building itself up and ignoring the plights of the world which surrounds it. Unfortunately, their calm is shattered when a strange craft falls to earth on the Eastside of their island. Leading to the first man to ever grace their shores since they isolated themselves from the world.

With the Vinetan Campaign squared-away and Man's homeworld tucked firmly under the Nation's shoestring belt, the Invasion of Kitezh now starts in earnest. The penultimate smackdown with the Empire's regent-lords is coming and out in the void beyond the Oort, a scouting ship cashes-in its ticket to safety as the Office of Naval Intelligence fires-up its latest Forerunner toy.

T-Force, those that'd broken off from the Founders during the early stages of the war, helped form the Resistance. A skirmish for an old AFB near Wichita turns sour for Lieutenant Church as he and his troops are forced to engage the Wireheads, only for the unexpected to drop into their lap:A new, friendly and highly-advanced human faction seeking to help rid the world of Legion.

On the way down to New Mombasa, Rookie falls into the Slipspace Rupture and ends up crashing down on Menae, high above Palaven, right in the midst of the Reaper War. From there, the war itself will shift and the fighting persists, but who knows what an ODST will add to the mix. (Redo of an older story)

After the pyrrhic victory of the Human-Covenant War, the Covenant was split into many warring factions vying for the power of old. The UNSC was left, bloodied, but as the sole power in the Milky Way for now. After an incredible discovery within a set of Forerunner Ruins, an Exploration Fleet with Doctor Halsey at its head is sent out. What they find will change everything.

Ever heard of a giant Megacorp falling down from the sky? Neither did Night City. Until a suriving group of UNSC came down with a mishmash of a UNSC Carrier ship. That certainly gave Night City something to talk about for months. (Inspired by both the main Halo series and Red vs Blue)

The Human-Covenant war had left an undeniable scar on the galaxy. Now in the year 2553, a new enemy shall appear, and a new war shall begin, one with origins in a time before the Halo Array.

After John-117's battle on board Mantle's Approach, the Spartan finds himself, with Cortana in tow, sent to a different world, where monsters roam the wilds, Humanity is confined to 4 major Kingdoms and where Magic and Tech coexist. The Spartan will soon have to join the ranks of the good guys against a horrid threat, whilst also on the lookout for fellow Spartans.

An opportunity he thought he'd never get. Damon is a 3rd generation SPARTAN who had everything taken from him, like most other 3rd generation recruits. Despite that, he managed to find a new home and a new family. But what if he had the chance to see his old one again? A companion story to Wrong Place, Right Time: A Hero's Story

It's been years since Noble Six and Auntie Dot found themselves in an alternate Earth being ravaged by a deadly plague. Now, a new threat emerges in the form of evolved and highly intelligent apes. Can Six and Dot ensure mankind's dominance? Or will they fall in the wake of the Ape uprising? Cover image does not belong to me.

Hundreds of millions of years ago, Humanity, Forerunners and the SanShyuum, the tier-1 species protected the galaxy. But the peace never lasted as the threat of flood and the reapers brought the Milkyway to the edge of extinction. Now the warriors of the past needs to guide the future galaxy and stop history from repeating itself.

Whilst exploring the depths of Gamma Halo, a lone Spartan inexplicably finds himself transported to an irradiated wasteland on a planet that shouldn't have one; Earth. Looking for a way to support himself, he teams up with a local courier investigating a series of mysterious disappearances from the city of New Vegas.

2537. The UNSC tries to find a new home for humanity to settle in, one away from the Covenant's reach. An old Punic-class supercarrier was chosen to do so, but a Covenant battle group pursues her relentlessly, until a black hole ends their chase. As both sides stumble in a new universe, the question remains: Will they bring their war to Azeroth? Or will they find a new beginning?

How can one man change a world ravaged by corruption, war, and poverty? And if that world isn't his own, why would he want to? In a life built out of discontent and fear, maybe the opportunity for change lies in a new place and a fresh start. A new beginning. And, maybe, he can look forward to a better tomorrow. - A companion story to Wrong Place, Right Time: A Hero's Story.

The journey of a hero doesn't always start where they expect. It doesn't always happen to those who expect it. Damon was never interested in being what SPARTANs represent: an implacable force for good standing as humanity's shield. Like most other third-generation SPARTANs, the war took everything from him. All he wanted was to return the favor. Sometimes we don't get a choice.

On the night Harry would have been dropped off by his Aunt, Dumbledore had someone else in mind. What if Harry was taken in by other strong people and they even decided to train him? Trained to be a Warrior by Wolves and the UNSC, he will change the world. OP, smart, trained Harry, small harem double cross with Witcher and Halo

After discovering a strange artifact in the abandoned Abydos Desert, the girls of the Foreclosure Task Force mistakenly activate it, sending themselves to a new and alien reality, one where humanity is in the brink as an Alien Armada bears down upon her worlds and death looms ever so close to them. Their hope for survival now rests on their own skill, a little luck... And the Halos

Her Metroid DNA took over, resulting in a monstrous transformation. Unable to control her powers, when escaping ZDR, her ship loses power. She can't remember what happened after that, but now, all she sees is the blackness of space, left drifting, alone. In the distance, the broken body of a frigate is seen, with the name of Forward Unto Dawn… Eventual Samus X Master Chief romance.

When the spirit of fire fled the world of Trove, they did not expect that an improbable event would upset their future and that of the inhabitants of Earth. The survival of humanity could well depend on their decision.