As the HECU Marine units made their way through the abandoned halls of Black Mesa, they were met with fierce resistance from the alien creatures that had overrun the facility. It was clear that their standard tactics were not working against these otherworldly foes.

Desperate for a solution, the HECU command turned to a private military company known as the Diamond Dogs. The Diamond Dogs were renowned for their elite soldiers and advanced technology. They were the go-to choice for any military operation that required the utmost precision and skill.
The HECU command contacted the Diamond Dogs and made a generous offer for their services. The contract was for a full-scale assault on Black Mesa, with the goal of not only eliminating the alien threat, but also retrieving valuable research data and materials from the facility.
Without hesitation, the Diamond Dogs accepted the contract and immediately mobilized their forces. They arrived at Black Mesa with their state-of-the-art weapons and equipment, ready to support the HECU Marines.

At first, the Marines were wary of working with mercenaries. They were used to operating on their own, without the help of outside forces. But as they witnessed the Diamond Dogs in action, their doubts quickly vanished.
The Diamond Dogs were a well-oiled machine, operating with precision and coordination that rivaled even the most highly trained military units. They moved through the halls of Black Mesa with ease, quickly taking out any alien resistance they encountered.
Their advanced weaponry and technology gave the Marines a much-needed edge in the battle. The Diamond Dogs had brought with them experimental weapons that were far more effective against the aliens than the standard issue HECU guns.

As they battled their way through the facility, the Diamond Dogs also provided valuable intel and strategic advice to the Marines. They knew the layout of the facility inside and out, and were able to guide the Marines to the most important areas.