Vigilance

Robert Jackson Bennett's Vigilance is a dark science fiction action parable from an America that has permanently surrendered to gun violence.
 
The United States. 2030. John McDean executive produces "Vigilance," a reality game show designed to make sure American citizens stay alert to foreign and domestic threats. Shooters are introduced into a "game environment," and the survivors get a cash prize.

The TV audience is not the only one that's watching though, and McDean soon finds out what it's like to be on the other side of the camera.