Ilima was a human city located within the Jacinto Plateau on Sera. It was one of three that surrounded Jacinto Plateau, and was defended by COG military forces. A major battle took place there nine years after E-Day, during which General RAAM personally led a massive assault upon the city, as he and his Horde manipulated the Kryll to cover the city in darkness by inking the skies using Nemacyst. The city was later destroyed in 14 A.E. by the Locust Horde tunneling underneath it with a Riftworm, sinking the entire city.
Ilima City, like most major cities on Sera, was attacked on Emergence Day by the Locust Horde. Among those killed was Jace Stratton's family. Debris from their home then fell on Jace, who was too small to lift it up, and was being hunted by the Locust, accompanied by a Berserker. However, COG soldiers came just in time and took out the Locust. Jace was still trapped, but was then saved by Dr. Gregory Wisen, who was the Principal of Ilima High School and Children's School of Hope. Wisen then brought Jace to his orphanage where he took care of him for the next nine years.
Evacuation of Ilima City
In 9 A.E., Queen Myrrah and General RAAM of the Locust Horde launched a full-scale assault on Ilima City by implementing a Kryllstorm, in which Seeders launch Nemacysts to expel ink in the sky and block out the sun, allowing the Kryll to invade during the day time and allow the Locust to occupy Ilima. When the COG learned of the Locust's advance, they sent their forces to help evacuate civilians instead of taking a stand against the Locust.
Four hours prior to the Kryllstorm, most of Ilima had been evacuated save for a few checkpoints that were prematurely attacked by Locust. This attack nearly wiped out every human who resided in the city. Zeta-Six was sent to Ilima to help evacuate the survivors, but received information from recused resident Jace Stratton that his foster father, Dr. Gregory Wisen, had not yet evacuated. Zeta traveled to Ilima High School where they learned that he went to his orphanage to gather the children for evacuation. Using the Hammer of Dawn via a Mobile Command Center in Ilima City Hall, Zeta cleared out some of the Seeders in the area in order to restore communications and hopefully buy the evacuation some more time. However, by this point, the evacuation was over and Zeta were the only Gears left in Ilima with only about 20 minutes left.
Zeta was able to successfully evacuate Jace, Dr. Wisen, and the children from the orphanage, but received losses in their squad as well. Ilima was then lost to the Locust when the Kryllstorm finally enveloped the city and killed all of the remaining humans, allowing the Locust to use the city as a stepping stone for invading the COG capitol of Ephyra.
In 14 A.E., the COG launched the Lightmass Offensive that bombed the Outer Hollow, destroying most of the Kryll. Due to the extinction of the Kryll and death of General RAAM, the city was once again under COG control. During the six month period following the Lightmass Offensive, the Locust launched an attack on Tollen Dam. Losing the Tollen Dam meant losing power to the remnants of Tollen, Speyer, Fort Reval, Montevado, and Bronn. The loss of power was imminent, and because of Speyer's proximity to Tollen, all resources and workers were transferred to Ilima City.
Operation: Hollow Storm
Within those six months, the cities of Tollen and Montevado sunk. The COG believed it was by the Locust. Fearing Jacinto City was next, the COG launched a full-scale assault into the Inner Hollow known as Operation: Hollow Storm. After a few hours of battle in the Inner Hollow, seismic activity was reported beneath Ilima City. The COG feared the worse and began to evacuate soldiers and civilians from the city. Underground forces were ordered to find the source of seismic activity, only to discover the source was a ten-mile long Riftworm that ultimately sank the city.
COG forces gathered in the Ilima sinkhole and was the site of the Battle of Ilima. The sinking of Ilima was witnessed by Delta Squad, who navigated through it on their way to the Hollow. Though it had been evacuated beforehand, a number of Stranded had remained behind, and were hunted down by Locust patrols. The Locust presence was later eradicated by Delta, but the remains of the city were swallowed by the Riftworm. Anything that wasn't was flooded when Delta sank Jacinto City themselves and flooded the Hollows in an attempt to kill the Locust off.
In 17 A.E., the Imulsion Countermeasure Weapon was activated and finally ended the Locust War. The COG then began to rebuild society by recycling the rubble from the ruins of Seran cities to build Settlements. During this time, the COG recycled rubble from the ruins of Ilima to build Settlement 5. A COG turret used during the conflicts of the Locust War was salvaged and refurbished for display in Settlement 5's Transit Station.
By 42 A.E., the Locust, who were thought to have been dead, reemerged as the Swarm and began their invasion. Sgt. Marcus Fenix led a rescue mission to find Reyna Diaz, the daughter of Kait Diaz, at the Swarm Hive located inside the Tollen Dam. During the mission, Marcus' team restored power to the dam and from there, the cities it supplied in order to use the radio tower in Speyer. One of the cities that had its power restored was Ilima.
- Gears of War: Judgment (Mentioned only)
- RAAM's Shadow
- Hollow (Appears in flashback(s))
- Gears of War 2 (First appearance)
- Gears of War 4 (Multiplayer only)
- Gears 5 (Mentioned only)