I would think that the two current Gears of War games set themselves up well for movie adaptions. 14 years after the Locust begin a war with the denziens of Sera, the outlook for the COG is bleak. The story would follow Marcus Fenix and the rest of Delta Squad as they attempt to recover the resonator to map the Locust tunnels and set off the Lightmass bomb to obliterate the Hollow. A good screenwriter could flesh out the mystery surrounding Marcus's imprisonment at the beginning of the game, as well as what happened to Marcus's father. I think these games set themselves up to be a trilogy, much like the game franchise is.