After a clever prologue that takes you through some of humanity’s toughest battles (E-Day, Anvil Gate) you take over JD Fenix-yes, Marcus’s son. Too bad “And they lived happily ever after” isn’t suitable sequel fare. The Cog, the Stranded, the last dregs of humankind-they’ve been left to rebuild some sort of approximation of prewar civilization, as best they can. With Marcus Fenix and the gang’s actions, the Lambent are gone.
Taking place 25 years after the apocalyptic events of Gears 3, humanity’s had a pretty peaceful time of it. They’re nothing you couldn’t have guessed anyway, given it’s a Gears game. NOTE: There are light spoilers ahead, though I think all of them were covered in the game’s marketing.