The original X-COM game, known as UFO Defense in North America, was released, laying the foundation for the franchise.
Firaxis Games released X-COM: Enemy Unknown, a reboot of the X-COM series, to critical acclaim.
Firaxis officially announced the development of X-COM 2, the sequel to X-COM: Enemy Unknown.
X-COM 2, the turn-based tactics game and sequel to X-COM: Enemy Unknown, was released for PC.
Firaxis announced the major expansion pack 'War of the Chosen' for X-COM 2, adding new content and features.
The 'War of the Chosen' expansion for X-COM 2 was released, enhancing gameplay with new factions, enemies, and missions.
X-COM 2 was launched on PlayStation 4 and Xbox One platforms, expanding its availability to console players.
The original X-COM project is formed as a global defense initiative against alien threats after the First Alien War.
X-COM successfully defeats the alien invasion, forcing the aliens into retreat and ending the First Alien War.
Due to public discredit and the rise of the Advent Administration, X-COM is disbanded and declared a rogue organization.
The Advent Administration, a front for alien occupation, establishes worldwide control and suppresses dissent through propaganda and force.
Underground resistance reactivates X-COM to oppose Advent's rule and the alien occupation of Earth.
X-COM operatives successfully extract the Commander from Advent imprisonment, enabling leadership in the fight against Advent.
X-COM establishes a mobile command base aboard the Avenger, providing flexibility to fight Advent forces worldwide.
X-COM uncovers alien technology related to psionic powers, developing countermeasures and training operatives in psionics.
X-COM commences covert operations and guerrilla warfare tactics to disrupt Advent's hold on Earth.
X-COM successfully sabotages the Avatar Project, halting the alien plan to transform humanity and solidify control.
