Half-Life 2

"Half-Life 2 takes place approximately twenty years after the incident at the Black Mesa Research Facility from the first game, in which scientists accidentally opened a portal to the hostile dimension Xen. The game begins with Gordon Freeman being awoken from stasis by the mysterious G-Man, who reveals that the Black Mesa incident attracted the attention of a multidimensional empire called the Combine, which conquered Earth in seven hours. The Combine have implemented a brutal police state by biologically assimilating humans and other species. The G-Man inserts Gordon into a train arriving at City 17, the site of the Combine Citadel, where Dr. Wallace Breen, the former Black Mesa administrator who negotiated Earth's surrender, governs as the Combine's puppet ruler. After eluding the Combine forces, Gordon joins a resistance (...)" - Half-Life 2's Wikipedia page, accessed June 21, 2021