The Virtual Army set up camp for nine days this month outside the Six Flags Great America amusement park here. Ads throughout the theme park touted the Army’s attraction. One read: “Bumper cars or fully loaded Humvees?” A chain-link fence cordoned off the Army’s 19500-square-foot exhibit. VAE adviser Lt. Col. Randall Zeegers, 6 feet 5 inches tall, saluted children as they passed and posed for pictures. “There’s no sales going on here,” said Lt. Col. Zeegers, who added that the goal of the VAE is primarily to educate the public. “It’s another way to tell our story ourselves.” Those who want to try the game are asked for their age, address, phone number and email, and the information is entered into a database. Players are also asked whether they want to join or learn more about the Army. Local recruiters can contact promising leads, if they are at least 17, within 24 hours. Players file into an air-conditioned trailer, filled with computers and Xbox 360 consoles, where they wait to be briefed. Then Staff Sgt. John Harper explains the mission: Genocidal indigenous forces are attacking international aid workers. It’s up to the players to protect them.