https://www.gamespot.com/articles/call-of-duty-black-ops-4-early-review-blackout-zom/1100-6462428/

Call of Duty: Black Ops 4 is out now, and it continues the franchise's history of explosive multiplayer, first-person shooter combat. Old mechanics and features return, such as the fan favorite Zombie mode, but the game implements several changes to the Black Ops formula. We've compiled everything we know about Black Ops 4 below.

Black Ops has a pretty lengthy history. The first, releasing in 2010, takes place during the Cold War in the 1960s, switching between CIA operatives Alex Mason and Frank Woods. 2012's Black Ops 2 moved the story to 2025, following Alex's son, David Mason. 2015's Black Ops 3, continued the previous game's journey into the future and followed operatives in 2065.