Gears of War takes place on an Earth-like planet known as Sera, inhabited by the human survivors of a once-glorious civilization. For a millennium, however, they fought among themselves, culminating in a battle to control Imulsion, a phosphorescing, low-viscosity fluid. Discovered by an oil-exploration drill, it was unusable until a woman named Dr. Helen Cooper created the Lightmass Process, which enabled production of cheap energy. The world economy soon collapsed due to its extremely low price and the elimination for the need of hydrocarbon and nuclear fuel sources. The few countries that had an overabundance of Imulsion under their feet soon found themselves at war with nations who were not as lucky, and so began the Pendulum Wars. During the seventy-nine year war, the Coalition of Ordered Governments, or COG, became a legitimate minor political party. Founded long before the Pendulum Wars by fanatical socialist Alexiy Desipich, the party was based on an obscure world-government philosophy based on eight guiding principle values: Order, Diligence, Purity, Labor, Honor, Loyalty, Faith, and Humility.
The Pendulum Wars finally ended with the COG establishing control over Sera, with magnificent cities and culture returning to the war-torn planet. Many believed a new golden age was upon them. This belief was crushed on what is now called Emergence Day. In less than twenty-four hours, a ravenous species known as the Locust Horde attacked every major city, leaving a quarter of Sera's inhabitants lying dead. By the time human forces pulled together to form a effective defense, it was too late. The Locust Horde took control of nearly every urban, military, and manufacturing center and quickly crushed Sera's valiant defenders. Billions lay dead. The COG took matters into their own hands and reenacted the Fortification Act, allowing martial law to be placed on all remaining survivors from the initial invasion. All survivors were ordered to evacuate to Jacinto Plateau, the only haven the Locust Horde could not penetrate from underground due to its thick granite substrata. Survivors who could not make it to the plateau were given the following apology: "For those citizens who can't make it to Jacinto, the Coalition appreciates your sacrifice. Please forgive us, this is the only way." Chemical and orbital particle laser weapons were launched to eradicate the Locust Horde in infested areas, denying them from using any cities or military installations, scorching the planet. 90% of Sera's surface became a wasteland, but the Locust Horde continued to survive by staying in their underground warrens.
Meanwhile, Jacinto was being fortified into an unassailable fortress. Its once magnificent cities, envied for their beauty, were soon turned into military use as defenses. The plateau's natural fissures and utility systems were destroyed or flooded with nerve gas to delay the Locust Horde's eventual attack. The survivors, or Stranded, living in horrible conditions and poor nutrition, had to find ways to defend themselves. When the Locust Horde began their attack, Marcus Fenix abandoned his post in a response from a distress call from his father, a renowned scientist, at the East Barricade Academy, but he was too late to save him. At his trial in the House of Sovereigns, Marcus was charged with dereliction of duty, cowardice, and failure to obey orders. Exempted from execution due to his exemplary tours during the Pendulum Wars, he was instead sentenced to forty years imprisonment at Jacinto Maximum Security Penitentiary. Four years later, the COG found themselves running low on able-bodied defenders, turning to untraditional sources of men; the infirmed, the young, and prisoners considered "irredeemable". As soon as the pardon was given, the Locust Horde overran the prison. The player begins the game here...
