On October 3, 2008, President George W. Bush signed the Troubled Asset Relief Program bill into law, delivering $450 billion to failing banks on the premise that it would prevent their collapse and stimulate a faltering economy. Like millions of Americans, Dmitri Williams, an associate professor of communications at the University of Southern California, found TARP troubling—not because the bill provided too much or (as many economists argued) too little, but because it was unscientific. “We did a half-a-trillion-dollar experiment with the economy and had no control group,” he says. Setting up a test bed for a program as complex as TARP might be difficult, but it wasn’t impossible. Williams had found just such a petri dish in videogames.