LV-742 is a planet rich in resources whose environment consists of deserts, jungles, and canyons with vast cave systems.
This resource-rich planet was first discovered by the Weyland-Yutani corporation, who quickly established oil refineries and mining facilities on several sections of the planet. During one of their resource-finding expeditions in a small cave system, they discovered a chamber containing dormant creatures known as the Xenomorphs. The Xenomorphs awakened and subsequently began to breed, restoring their population and killing the small expedition's entire team.
The Xenomorphs then began to attack a nearby oil refinery, resulting in heavy civilian casualties. The USCM, initially accompanying Weyland-Yutani personnel merely to provide token security, immediately began to mobilize for war in order to exterminate the Xenomorph threat. Due to the difficulty of the task, they eventually partnered with Weyland-Yutani in hope of stopping the Xenomorph infestation, but further complications ensued as the Predators of many aspiring clans joined the conflict, using it as part of their ritual to become the ancient Predator council's successors.
With Colonial Marine forces hard-pressed to contain the Xenomorphs and combat the Predators simultaneously, Weyland-Yutani science teams decided to expand their research on the Xenomorphs by requesting that USCM High Command deploy Marine combat teams to neutralize an entire Xenomorph hive, but collect a Praetorian cocoon as it instinctively begins to morph into a new Queen; Marine combat teams were successful in this endeavor, sending the cocoon to Weyland-Yutani for experimentation. With this major sample in hand, head Weyland-Yutani researcher Samuel Kadinsky began researching on the Xenomorph lifecycle which led him to the creation of the K-Series. His additional research on the Predators angered the ancient Predator council, and they assaulted his research facility, kidnapping the doctor and torturing him to death as punishment.
Meanwhile, as Colonial Marine strongholds across the planet were besieged by Xenomorphs, USCM High Command was notified of Kadinsky's kidnapping and the devastation of the research facility. Facing this dire situation, High Command concluded that Xenomorph containment and extermination was impossible while Predators were allowed to roam free. At last, the USCM resolved to annihilate the Predator presence on LV-742 once and for all with a series of combat operations designed to clear the way for an all-out assault on the enemy headquarters, the Predator Fortress.
The conflict between the three species eventually ended with the Colonial Marines destroying the Predator Fortress with heavy demolition charges, the Predators killing the PredAlien Queen and sterilizing the PredAlien hive site with a nuclear device, and the Xenomorphs exterminating the K-Series in order to keep their genetic strains pure.