Shepard gets off the elevator, and begins his fight against the many Black Ops that have fortified themselves throughout the Level 4 Storage Unit. Traversing the storage unit, Shepard sees that the aliens of Race X have broken in as well, and are now battling it out with the Black Ops. The corporal also starts seeing the small glowing sprites again, and tries to follow after them. Shortly after, Shepard comes across a weapon storage room with a Black Mesa security guard in it. The guard warns the corporal to stock up on supplies because something below them is coming through, and that it's the nastiest thing he's ever seen.
Taking the elevator down deeper into the Level 4 Storage Unit, Shepard once again sees the glowing sprites and follows them. He enters into a room with a giant portal that all the small sprites are being drawn to, which the sprites appear to be powering up the portal. Eventually, a massive Race X creature known as the Gene Worm starts to crawl through it trying to establish itself on Earth in order to begin terraforming the planet to better suit Race X. Shepard uses the two laser cannons in the room to blind the Gene Worm's eyes, which results in its stomach opening up for the corporal to land a brutal hit at its core. This process is repeated several times until the Gene Worm is killed, but the death of the Gene Worm causes the portal to go unstable, and overtakes Shepard.
This Chapter contains examples of:
- Attack Its Weak Point: The Gene Worm's weak point is a portal contained in its belly. When shot, the Worm retaliates by summoning a Shock Trooper from this portal. Defeating the Gene Worm requires blinding it in both eyes with the stationary laser cannons, which opens up its stomach to be shot at. Repeat this process several times, and the Gene Worm will eventually die.
- Boss Battle: Shepard takes on the Gene Worm, a large Race X creature trying to enter a portal onto Earth.
- Suspicious Videogame Generosity: You enter a room full of weapons and ammunition. Shortly after, you're taking on the game's final boss.
