GRAPEVINE, Texas--(BUSINESS WIRE)--According to a recent study by GameStop, a family of specialty retail brands that make the most popular technologies affordable and simple, approximately two in five gamers are leaving upwards of $200 unclaimed by holding on to unused video games, meaning gamers are literally leaving money on the table. The specialty retailer, which in 2014 gave gaming fans more than $1 billion in trade credit, surveyed more than 400 video game enthusiasts to learn about their