https://www.gamespot.com/articles/rainbow-six-siege-outbreak-and-chimera-update-now-/1100-6457186/

The latest free expansion for Rainbow Six Siege, Operation Chimera, launches today, thereby kicking off Year 3 for the popular shooter. This is a more substantial update than usual, as it adds new content to not only the core, competitive multiplayer component of the game, but it also introduces a new co-op event mode for a limited time. Chimera is now live on PC and is in the process of rolling out on PS4 and Xbox One.