Not unlike HALO's own ring-like orbital space stations the Arc in 'ArcRunners' is also a self-containing satellite ecosystem for it's otherworldly inhabitants. Those inhabitants being robotic androids, and human cybernetic hybrids. All governed by an AI system that is there to maintain order. Unfortunately for the Arc, and it's robotic citizens a virus infiltrated the AI system turning all those tied to it into mechanized maniacs.
Thanks to an onboard counter-intelligence operative though you were summoned, or rather re-atomized, to save the day. Using one of three class based builds including the soldier, ninja, and hacker you set forth to reclaim each district utilizing the dropped weaponry, and augment upgrades to your advantage. All in a goal to stop the virus at it's source.