Gears of War 4 takes place 25 years after the events of Gears of War 3 which saw the wiping out of the Locust and Lambent threats. Though this was a victory for humankind, the Coalition of Ordered Governments has grown concerned over the dwindling human population. Estimates suggest only hundreds of thousands of humans remain, and so walled-off cities are built to protect the citizens from danger.
Some humans didn’t like what the COG were doing and so chose to live their own life outside of the walls of the cities. Without resources of their own, however, they continue to raid COG territory to steal and pillage what they can.
In terms of what’s going on in the actual game, players will be assuming the role of Marcus Fenix and Anya Stroud’s son, J.D. Fenix, who, with his friends Del and Kait, takes on a new threat: the Swarm.