It was a scene that could have been pulled straight from Arma 3 or Squad, the military simulation games that 21-year-old Jack D. Teixeira has spent literally hundreds of hours playing. Teamwork and communication are the keys to completing these missions. And this time, the squad was minutes away from achieving its objective. DIGHTON — The air was still, and the sky was clear when the men in tactical gear arrived at the two-story brick colonial. An armored vehicle crept to a standstill in the driveway. One agent popped out of the turret and trained his rifle at the front...