Ufo: Enemy: Unknown

Interrogating high-ranking alien captives reveals that the various species are being manipulated by a master race. The Revelation

Late-game research uncovers the truth: the invasion is being orchestrated by the , a highly advanced, psionic race that has enslaved other species to serve as their military arm. Their primary base in the solar system is located in the Cydonia region of Mars. The Final Assault: Cydonia UFO: Enemy Unknown

You discover that alien technology relies on Elerium-115 , a stable heavy element not found on Earth, which becomes the most vital resource for humanity's advanced crafts and weapons. a highly advanced

The story continues in X-COM: Terror from the Deep , where a second wave of aliens awakens from the ocean floor. UFO: Enemy Unknown