Lore. Siege comes from a time where mobas, online shooters and other multiplayer games were big on building a “universe”. Every single one of the operators had full bios, and some also had videos about them. They also had videos explaining in-universe events, such as the alien virus that introduced the two agents from CBRN (Chemical, Biological, Radiological and Nuclear Threat Unit), Finka and Lion, and had an entire special pve game mode made for it, that eventually became its own spin-off game.