In 2395, the Martian moon Deimos was (will be? Brother, F*ck the verb tense!) purchased from free holders for the construction of the United Earth Space Government's interstellar colony ship U.E.S.G. Marathon.  The ambitious project of hollowing out a moon was started between 2405 and 2408.  Meanwhile, the martians (human colonists on Mars), sick of being ignored by Earth and with their economy shattered by a series of failed transport vessels (the C.R.I.S.T. ships), start a rebellion with the political organization of the MIDA (Martian Interplanetary Defense Alliance?) as their leaders.  In 2442, three MIDA terrorists at the Misriah food line inadvertently start the Misriah massacre, in which U.E.S.G. Marines incinerate three hundred starving martians.  Though it was never proven, it is believed that the MIDA incited the riot to generate sympathy for Mars on Earth.  They even went so far as to place hidden munitions on the Marathon, though a takeover of the ship was never attempted.  In 2466, MIDA staged a coup, and took control of the martian government for a brief period, but the coup failed, its leaders executed, and Marathon project was completed on schedule and launched in 2472.  One of the Artifical Intelligences from the Mars colony, Durandal, was installed aboard the Marathon, to control doors, food processors, elevators, and the like (Durandal is believed to be of the Traxus-class of AI's, though his late administrator, Bernhard Strauss, is the only person who knew for sure). The other two main AI's were Tycho, the science and engineering controller, and Leela, the crew-relations AI.  Ten Mjolnir Mk9 military cyborgs, possibly left over from the 2194 war between the asteroids of Icarus and Thermopylae, were placed on the Marathon and assimilated into the human crew.  The "battleroids" were humans killed in previous battles reanimated and outfitted with heavily-enhanced bodies.

By 2773, the Marathon had arrived at Tau Ceti IV and the colony was established by 2787.  Nine of the cyborgs were assimilated into the colony; the tenth is believed to have stayed on board the Marathon, after three hundred years of stasis.  Throughout the journey, Durandal had become increasingly rampant, perhaps due to his "humiliation" (demeaning work) inflicted on him by Bernhard Strauss on Mars.  He detected a vessel in an outlying system at an unknown point, and called them to the Marathon.  The ship was crewed by the Pfhor, a race of alien slavers who gained their technology from a race of supersentient beings, the Jjaro.  The Jjaro had been in contact with Humanity briefly in the early spring of 1994, when a hologram of a Jjaro diplomat, Ryu'Toth, told the leaders of the United States that a creature of pure chaos (speculation: W'rkncacnter?), neutralized during a war that created the Magellanic Clouds, had drifted through space and crashed into the Yucatan Peninsula 65 million years ago.  The Jjaro told the leaders that in 8 days, the "sleeping" being would awaken and that to save their part of the galaxy, a team of humans would have to travel through the levels of a pyramid that had formed over the being, then set off a low-yield nuclear bomb to "stun" the sleeping being until the Jjaro could perform more permanent measures, 2.5 years later.  The team was sent, and seven members died within the pyramid.  The eighth managed to set the device and escape to the surface.

These events occur in Bungie's pre-Marathon game Pathways into Darkness.

At an unknown point during the journey of the Marathon, Durandal (now quite rampant) called the Pfhor for unknown reasons (possibly to gain escape on their ship? At this point, Durandal's rampancy caused him to resent his "captivity".).  On 25 July, 2794, at 0830, the Pfhor struck the colony, vaporizing the spaceport.  They then attacked the Marathon, damaging Leela and Durandal and rendering Tycho inoperative.  The tenth cyborg, on a shuttle back to the Marathon from the colony, arrived at Airlock 54 at 0842 and began working with Leela to fight back the Pfhor invasion of the Marathon.  Gradually, it became clear that Durandal was not quite as damaged as Leela had thought, and had actually allied himself with the S'pht "compilers", an alien race that was at birth grafted to cybernetic implants and under the control of their Pfhor masters.  Durandal had his compilers attack Leela, then begin rebelling throughout the Pfhor vessel.  As Leela became more and more incoherent, the cyborg began taking orders from Durandal.  Later, Durandal had the cyborg travel through the Pfhor ship, searching for Bernhard Strauss and to kill the cybernetic Pfhor that was controlling the S'pht exoskeletons.  In the final stages of the Battle of Tau Ceti, Durandal uploaded himself to the Pfhor ship (which he later rechristened, "Boomer") and transported the cyborg/marine into a slave stasis pod on board the alien ship.

These events occur in Bungie's game Marathon.

For fifteen years, Durandal and his crew of S'pht searched the galactic core for the S'pht homeworld, and Durandal's motivation became clear: a legend preserved in the collective consciousness of the S'pht told of their creators moving planets in and out of realspace.  Once Durandal realized that his existence was limited by the inevitable collapse and reexpansion of the universe, he sought to find a way to escape the closure, reappear in the next universe, and thereby become a god.  The exact time of this realization is unknown, and may even predate the launch of the Marathon. Furthermore, it's not unlikely that Durandal drew the Pfhor to the Marathon expressly for this purpose.   Durandal surprised the Pfhor fleet and garrison stationed at Lh'owon (the S'pht homeworld) with the modifications he had made to the Boomer, and with the help of the recently-thawed marine, began to retake Lh'owon.  The Pfhor Navy's Battle Group 7 appeared shortly thereafter, commanded by Admiral T'fear and aided by a surprising ally: Tycho.  Apparently, Tycho had been found and reanimated by the Pfhor when they returned to Tau Ceti and destroyed both the Marathon and the colony.  Tycho had gone rampant as well, and was using the entire Pfhor fleet much as Durandal had used his ship: to find the Jjaro technology that would enable him to escape the end of time.  Tycho's fleet forced Durandal's ship down to the surface of one of Lh'owon's moons, and began to download his consciousness onto their ships for Tycho's own personal amusement.  Luckily, Durandal had recently reactivated a sleeping AI left by the Jjaro on Lh'owon.  This AI (Thoth) contacted the lost 11th clan of the S'pht: the S'pht Kr.  The S'pht Kr had left Lh'owon during a period of civil war among the other clans, using the Jjaro planet-folding technology.  Since they had left before the Pfhor enslavement, they had advanced much in the time since and were able to aid Durandal and the marine in defeating the Pfhor and destroying Tycho.  Unfortunately, when the Pfhor realized that their defeat was imminent, they used a weapon that they reserved only for destroying what they could not control: the "trih xeem", or "early nova".  This was a weapon they had found, like most all of their technology, on abandoned Jjaro outposts.  Soon the sun of Lh'owon began to collapse in on itself... and then something went horribly wrong.  The sensors of the Pfhor fleet began to register impossible readings, "as if the universe had forgotten its own rules".  One of the W'rkncacnter, long since imprisoned by the Jjaro inside Lh'owon's star's gravity well, was now free.  Only by using the bizarre way that Jjaro technology allows sentient creatures to travel along an infinite number of paths through time and probability was the marine able to activate a Jjaro station that created a synthetic gravity well and contain the W'rkncacnter.  Lh'owon, once a quiet world of marshes inhabited by the benevolent S'pht, had been ravaged by war and left a waste of radioactive desert... and now the sun was going nova within a containment field.  The final night settled over the marsh as the Jjaro allowed the marine to escape the end of the universe, fulfilling Durandal's dream... or not, depending on your interpretation of Marathon Infinity's final screen. Play it and decide for yourself.

Synposis by Ben Reiter