20th century (1900-1999)
1908 CE
  • 30 June - The Tunguska Event
    A large explosion of unknown origins occurs near the Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia. Some people born in the region over the next few decades, as well as their descendants, will exhibit psionic abilities. Some of these people will be used as psychotronic agents by the Soviet Union during the Cold War.
1947 CE
  • 7 July - The Roswell Incident
    An unidentified flying object crash-lands on a ranch near Roswell, New Mexico. The wreckage is promptly recovered by the U.S. Air Force, and a cover-up claiming that the crashed object was a weather balloon is put in place. In actuality, the crash was of a "flying saucer" — a Sectoid scout ship. Three Sectoids, two dead and one alive, and plenty of technologically-advanced xeno-artifacts are recovered from the crash and whisked away to Wright Airfield in Ohio. This event makes the existence of alien life known to the U.S. government.
  • Creation of the Majestic 12
    In response to the Roswell UFO Incident, U.S. President Harry S. Truman issues an executive order forming the Majestic 12, a secret committee of scientists, military leaders and government officials tasked with determining how alien technology can be exploited and setting a framework for how the U.S. should engage with extraterrestrials in the future.
1961 CE
  • 19 September - The Barney and Betty Hill Abduction
    An American couple, Barney and Betty Hill, are reportedly abducted by aliens resembling Sectoids in rural New Hampshire. They are treated affably by the aliens, who study them briefly and present them with a stellar map pointing to Zeta Reticuli before returning them safely.
21st century (2000-2099)
2015 CE
  • Reports of the UFO activity increase thoughout the world. As reports continue to increase, the legitimate press joins the tabloids in plashing "We Are Not Alone" headlines across the front page of major metropolitan newspapers all over the world.
2016 CE
  • Documented cases of human abductions by UFOs become commonplace in areas of sparse population in countries throughout the world. World governments step up their military readiness, and there is a general news blackout in most of the affected countries. Scientists try to make contact with the aliens, but there is no substantial response.
  • Many countries begin to contemplate a direct military strike against the aliens. Japan forms the 'Kiryu-Kai' , an anti-alien combat force. After five months of operation, using the best equipment available, the group is unable to intercept even a single UFO. Due to lack of funding, Japan is forced to disband the Kiryu-Kai in November of 2016.
  • 11 December - Creation of XCOM
    The United Nations Security Council holds a clandestine summit in Geneva, Switzerland. After much debate, it is unanimously decided that a covert, multinational force should be formed to investigate, combat, and (hopefully) defeat the aliens. Assembling the best pilots, soldiers, engineers, and scientists from all the funding nations, the Geneva council establishes XCOM — the Extraterrestrial Combat Unit.
2017 CE
  • January 1st - Activation of XCOM