"With the assistance of electronics wizard The Trachmann, your old enemy, The Trickster, has taken control of Central City. True to his warped sense of humor, he's made himself mayor and decided to get rid of you for good. Declaring you a common criminal, Mayor Trickster has put a price on your head so that every hoodlum and punk in the city is hunting for you in order to claim the reward for themselves. To make things even more interesting The Trickster has raided the city treasury and stolen five priceless gems which have been scattered around the city as bait in a madcap but deadly assortment of traps. And if that wasn't enough, The Trachmann has released an unstoppable FED (Flying Electronic Droid) which has been programmed to search Central City and destroy you."
Source: Wikipedia, "The Flash (Video Game)", available under the CC-BY-SA License.