The Hollywood Reporter writes that New Line tried adapting the game for awhile before, but then licensing rights lapsed. We can only hope that this turns out better than the most recent, long-in-development video game movie, Warcraft.
This isn't the first time Microsoft has flirted with Hollywood. However, a fundamental lack of knowledge for how the movie industry works rendered a Halo movie stillborn. It looks like since then, the folks in Redmond have learned a bit more about the movie business.
Gears of War 4 comes out October 11, 2016.