The father said he contacted the store and police, who took custody of the baggie.
The Calcasieu Parish Sheriff's Office said the substance inside the baggie was tested and confirmed to be methamphetamine.
Dustin Varos, a manager at the Game Stop, said the case would not have been opened for inspection if it was shipped from another store.
Joey Mooring, director of public relations for GameStop, said games are opened and checked for quality when they are returned or traded by customers. He said the games are checked again before being sent to other stores, but may not be examined again when they arrive.
"Any games traded in with us are checked for quality," Mooring told KPLC-TV, "then could be shipped to another store."
Investigators said GameStop does not have a method of tracking the game's origins.
Police have found bags of meth concealed in bizarre locations in recent weeks, including packages of Twinkies, Combos snack wrappers, stitched into footballs, and inside the lining of a traveler's luggage.