The Journal of Memories

It is the year 2054. Smart devices and robots are more developed. Everyone is reliant on machines and social interaction between people has lowered.One day bombs are dropped on New York. A gas spreads through the city making everyone pass out. When they wake up everyone's memories and their knowledge of the current world are gone. All accept for one teenager named Ben Foster, who slowly gets his memories back to him as he wonders around the city.The question is: Who created this gas and why was it dropped in New York?