- "Anya, it's a giant worm! They're sinking cities with a giant worm!"
- — Marcus Fenix to Anya about first seeing the riftworm for the first time
The Riftworms were massive worm-like creatures that were 8-10 miles long and half a mile across. Semi-intelligent creatures, Riftworms created the Hollow by burrowing through the crust of Sera and leaving behind their waste that enriched the soil and created life inside the Hollows. The Riftworm was viewed as a God by the Locust for being a life giver.
Building the Hollow and gods of the LocustEdit
Riftworms burrowed across the Seran crust, devouring everything in their path and leaving its manure which enriched the soil creating life inside the Hollows. The Riftworms created a majority of the Hollows and The Locust view them as gods. The Trinity of Worms was based around the Riftworm and Locust architecture would be based on the Riftworm. It was believed that the Locust would use pheromones or explosions to move the riftworm towards their target. The riftworms would later disappear until the Lightmass Bomb was used on the Outer Hollows which awakened one, giving the Locust their god to turn the tide of the war.
An awakened RiftwormEdit
In the fourteenth year of the Locust War, after the Lightmass Offensive, a single Riftworm was awakened by the massive explosion of the Lightmass bomb. High priest Skorge would use their god to begin a campaign on destroying Seran cities on Jacinto Plateau. For several months, COG outposts and two cities along the plateau vanished, forcing the COG to venture into the deepest areas of the Hollow to kill every single Drone to end the war.
Operation: Hollow StormEdit
- "Holy shit. Holy shit! HOLY SHIT!"
- — Benjamin Carmine, terrified after seeing the Riftworm for the first time.
With the assault on the Locust tunnels in the Inner Hollows, Delta-One was ordered to investigate seismic activity near, and beneath, the city of Ilima. After Delta assisted a Gear squad by killing the Locust's mortar crew and using their position to attack the Locust, Marcus, Dom and Carmine noticed that the "wall" was moving, and they realized that whatever was moving was the source of the seismic activity.
After getting through Locust defenses and opening a gate, Marcus, Dom and Carmine took cover as they noticed the "big shot" ride a Hydra and scream unintelligible language. The Riftworm then appeared and began sinking Ilima, and the Gears learned of its name and deduced that it had also sunk Montevado and Tollen several months ago.
The Riftworm would circle around the Ilima sinkhole, continuing to destroy it. Later, as Delta-One rescued Baird from Processing, they managed to signal a King Raven to pick them up. As the King Raven picked them up and began to leave, the Riftworm burst out from the ground and swallowed it.
Killing the Riftworm from InsideEdit
- "First we kill it, then we cut our way out!"
- — Marcus Fenix, deciding to kill the Riftworm from the inside before escaping it.
After recovering from the crash/swallowing, minus a missing Carmine, Delta battled their way through the worm, in an attempt to find its heart and kill the creature. Narrowly avoiding the many digestive systems in the Riftworm, they found Carmine but they were too late, as his stomach was already eaten by the Riftworm's secondary digestive system, the Nemacytes. In anger, Cole shot wildly, which resulted in the Riftworm sending a wall of debris down.
Delta Squad narrowly avoided getting crushed by the debris, and passed through several lethal obstacles that were part of the Riftworm's systems. They later encountered the heart and severed its arteries, but the Riftworm still continued. Baird deduced that there was more than one heart, and the Gears followed the sound of the remaining hearts and severed them.
After severing the third heart, the beast erupted out of the Seran crust a mile into the sky from a heart attack and massive loss of blood. It roared as it spat out gallons of blood and crashed to the ground dead. The Locust's advantage in the war was destroyed.
Delta cut their way out of it with their chainsaw bayonets, and were shot out in a stream of the creatures blood, narrowly avoiding drowning in it. 
Following the death of the Riftworm, the Locust plan was delayed, but not completely foiled. During the Siege of Nexus, Queen Myrrah could be heard broadcasting that even though the Riftworm is dead, the Locust plan to sink Jacinto continues.
If there were any other remaining Riftworms in Sera, their fate remains unknown after the flooding of the Hollows and the Imulsion Countermeasure Weapon's activation. Its possible that they drowned in the flooding of the Hollows since they wouldn't have been awake to escape.
Behind the scenesEdit
- Before the cutscene of the Riftworm sinking Ilima, the Riftworm makes several appearances before that. It is seen first before the first encounter with the snipers, in that tunnel that's filled with yellow fumes, when Anya says "Seismic activity getting stronger Delta", the Riftworm will be slowly moving on the left side. Then, it is seen again after saving the Gears squad from the heavy mortar fire.
- Inside the Riftworm, Delta Squad comes across the bodies of four Gears and one civilian, not including that of Benjamin Carmine.
- When the player passes by the Riftworm's digestive teeth, Dom will ask if the large hanging organ in the area is the heart, but Baird says no. If the player shoots it, the worm will gag, meaning it must be the uvula. (Which explains why Cole's excessive shooting of it caused a wall of debris to fall through the worm's throat).
- ↑ http://hawkprey.blogspot.com/p/old-junk.html
- ↑ http://1.bp.blogspot.com/-lqxZmQStnPE/TejUZ8zxqtI/AAAAAAAAAG8/VdE1M-J6yKY/s1600/Riftworm2.jpg
- ↑ Gears of War 2
- ↑ Gears of War 2 collectable
- ↑ Gears of War 2
- ↑ Gears of War 2