Competition for tech workers makes company culture a significant draw. LOS ANGELES — The engineers at Los Angeles startup Zefr needed to unwind after completing a months-long project. That’s when they entered the “War Room,” a specially built space inside the company’s offices with computers lined up against the walls for one purpose: computer game tournaments. For the rest of the day, teams of five with names like Shades of Greyscale and Sit the Flak Down heckled, cheered and battled one another playing a classic first-person shooter called “Unreal Tournament.” Winners got Nerf guns.