Eldon asks Jaiden if he's up for a challenge involving the Black Mesa facility, which he takes up. Eldon becomes G-Man and Jaiden becomes Dr. Boom. Later on, another Goon shows up.
The trio finds themselves outside, however, they soon realize how punishing it is outside compared to the facility. They race to get back inside and escape the hellish outside.
The goons wander into the Lambda Complex and slowly form to become the Lambda-busters. Ahead of them lies their final and most challenging battle yet: Xen.
The Lambda-busters fall into Xen, the border world of life. They are forced into several long, frustrating, and exhausting battles that take everything out of them. After, they meet Eldon's twin, who gives them an offer.