2012 - Mankind steps onto the moon's surface for the second time. Three hundred years later, mankind has colonized several planets within our solar system. But the time of prosperity and growth is about to come to an end. Alien forces begin invading the solar system, leaving nothing in their wake. It is up to Earth's newly created fleet of war ships to defend the system.

The 26th century. Humanity has expanded beyond Earth’s system to hundreds of planets that colonists now call home. But the United Earth Government and the United Nations Space Command is struggling to control this vast empire. After exhausting all strategies to keep seething colonial insurrections from exploding into a full-blown interplanetary civil war, the UNSC has one last hope.

In the 25th century, humans have conquered space. The advent of faster-than-light travel has opened up hundreds of habitable planets for colonization, and humans have exploited the virtually limitless space and resources for hundreds of years with impunity. So complacent have they become with the overabundance that armed conflict is a thing of the past, and their machines of war are obsolete and decrepit. What would happen if they were suddenly threatened by a terrifying new enemy?

Earth is no longer the center of the universe. After the invention of the faster-than-light jump drive, humanity is rapidly establishing new colonies. But the vast distances of space mean that the old order of protection and interstellar law offered by Earth has ceased to exist. When a nearby world attacks, the new colony of Glenlyon turns to Robert Geary, a young former junior fleet officer, and Mele Darcy, a onetime enlisted marine.

The Hundred Worlds have withstood invasion by the relentless Hok for decades. The human worlds are strong, but the Hok have the resources of a thousand planets behind them, and their fleets attack in endless waves. The long war has transformed the Hundred Worlds into heavily fortified star systems. Their economies are geared for military output, and they raise specialized soldiers to save our species. Assault Captain Derek Straker is one such man among many.

The Phage War had been a devastating conflict for the Terran Confederacy. Even with the destruction of their terrifying, implacable foe, humanity is still reeling. Political alliances are crumbling, and their mighty fleet is in tatters. There is nothing to celebrate, even after such a complete victory. They soon learn that there are other stellar neighbors - and they've been watching the conflict with great interest. One species comes with an offer of friendship and alliance, but humanity is weary and distrustful.

Earth is conquered. Sol is lost. One ship is tasked to free them. One Captain to save them all. When an alien armada destroys the United Earth Space Force and takes control of the human homeworld, newly reinstated Captain Annette Bond must take her experimental hyperspace cruiser Tornado into exile as Terra's only interstellar privateer. She has inferior technology, crude maps, and no concept of her enemy, but the seedy underbelly of galactic society welcomes her so long as she has prizes to sell and money to spend.

The Confederation has fought three wars against the forces of the totalitarian Union. Three generations of its warriors have gone off to war, held the line against the larger, more powerful enemy. Now the fourth conflict is imminent, and the Confederation's navy is on alert, positioned behind the frontier, waiting for the attack it knows is coming.

When the Colony on Hayden's world went black, a team was sent to investigate. It was supposed to be a training mission: skip in, find out the Casimir Transmitter had gone dead, report back and wait for resupply from the Fleet. By the time the only surviving member of the team made landfall, it was spectacularly clear that this wasn't a training mission.

After almost a century of peaceful exploration and colonization of space, the United Earth Space Force stumbles across a shockingly xenophobic alien race that has more and better armed ships and refuses all attempts at contact. As the outgunned Space Force is driven back in battle after battle in what appears to be a war of extermination, one officer experiences precognitive visions that help him blunt the enemy onslaught, but he can't control or predict when they occur.

A cease-fire that has lasted seven years... Worlds half-destroyed that have been rebuilt anew... Friends and crewmates scattered light-years apart... New leaders that would be kings... The Jung threat has been renewed, in ways not imagined. It will take a new savior to inspire the masses, and once again lead those willing to fight against oppression. But who will the new savior be?

Nate has a talent for space combat after hundreds of victories in the Star Crusader videogame simulation. His skills are unique, enough to gain him a rare privilege: the chance to join five other Alliance cadets and escape the dull routine of the classroom. They will enter a fierce competition light-years away in the ancient Byotai Empire. Yet days after their arrival a rebellious faction begins a bloody mutiny that spreads like wildfire. The time for competition has ended; the time of war has begun.

Harmon Tomeral wanted nothing more than to go to space. Sent to an orphanage when his parents were killed in a sandstorm, the odds were stacked against him. Despite that, he made it to the academy and graduated in the top 10 percent of his class...only to find out the fleet did what it wanted, regardless of regulations, and he came from the wrong planet. He didn’t give up his dream, though, because where there’s a will, there’s a loophole, and Harmon and his friends found their loophole in the Top Fleet Marine competition - the winner would get 100,000 credits....

The plot by the Galactic Union’s Mercenary Guild against the Four Horsemen has culminated in an invasion of Earth. Faced with an overwhelming force, the human mercs had no choice. They’ve fled, leaving Sansar Enkh to go to the Mercenary Guild headquarters on Capital Planet to stand trial for humanity. On the run, Jim Cartwright and Nigel Shirazi have travelled to the Winged Hussars’ secret base of New Warsaw, in an effort to convince Alexis Cromwell to join the fight, while the other mercenaries who escaped the fall of Earth have gone to the perceived safe haven of Karma.

Returning home after a training exercise, Captain Jonathan Somerville and his ship, HMS Achilles, stumble into the middle of the warzone. Stranded behind enemy lines, the crew of Achilles must fight their way through occupied territory if they are to link up with coalition forces and help turn back the invaders.