Gears of War 4 is now deep in development at Microsoft's internal studio The Coalition. However, a version of the upcoming Xbox One shooter was started by the franchise's original creators at Epic Games.
According to Game Informer:
After Microsoft bought the Gears of War franchise in 2013, it was sent all the files and technology Epic had created for Gears of War 4. The Coalition essentially raided Epic's "basement" to find the studio's story treatments and old pieces of concept art. Some of the things that are now in Gears of War 4, such as the idea of setting the game in the future, the idea that Marcus would have a son, and even the name JD were all ideas originally developed at Epic prior to the Microsoft sale.
Epic Games worked on their version of Gears of War 4 for six months before deciding to abandon its development. Epic is now working on other games, such as the free-to-play multiplayer shooter Paragon. Meanwhile The Coalition and Microsoft are scheduled to release their vision for Gears of War 4 sometime in late 2016.